广东省2017年小升初数学模拟考试试卷及答案

<strong><span>一、认真思考,我能填</span></strong><br><br><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024113040.png?m=0.8610172665229072"><br><br><span>2、用1、2、3、6这四个数写出两道不同的比例式是________.</span><br><br><span>3、8/________=________÷60=2:5=________%=________小数.</span><br><br><span>4、比40米多25%是________米.40米比________米少20%.</span><br><br><span>5、1/4</span><span>:1/5</span><span>化成最简的整数比是________</span><div><br><span>6、大小两个圆的周长比是5:3,则两圆的半径比是________,面积比是________. &nbsp;&nbsp;&nbsp;</span><br><br><span>7、1/b</span><span>=c,若a一定,b和c成________比例;</span><span>若b一定,a和c成________比例. &nbsp;&nbsp;&nbsp;</span><br><br><span>8、一个圆锥和一个圆柱等底等高,圆锥体积比圆柱少18立方分米,圆锥体的体积是________立方分米,圆柱的体积是________立方分米. &nbsp;&nbsp;&nbsp;</span><br><br><span>9、在比例尺是20:1的图纸上,量得图上零件是20厘米,零件的实际长度是________厘米. &nbsp;&nbsp;&nbsp;</span><br><br><span>10、一个圆锥的底面半径是3厘米,体积是9.42立方厘米,这个圆锥的高是________厘米. &nbsp;&nbsp;&nbsp;</span><br><br><strong><span>二、仔细推敲,我能辨</span></strong><br><br><span>11、圆锥体积是圆柱体积的 1/3</span><span>.(判断对错) &nbsp;&nbsp;&nbsp;</span><br><br><span>12、周长相等的长方形,面积一定相等.(判断对错) &nbsp;&nbsp;&nbsp;</span><br><br><span>13、在比例里,两内项的积除以两外项的积,商等于1.(判断对错)</span><br><br><span>14、图上1厘米相当于地面上实际距离100米,这幅图的比例尺是 1/100</span><span>.(判断对错)</span><br><br><span>15、把10克的农药溶入90克的水中,农药与农药水的比是1:9.(判断对错)</span><br><br><strong><span>三、反复比较,我能选</span></strong><br><br><span>16、圆锥的侧面展开后是一个(&nbsp;&nbsp; ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><br><br><span>A、圆</span><span><br></span><span><br></span></div><div><span>B、扇形</span><span><br></span><span><br></span></div><div><span>C、三角形</span><span><br></span><span><br></span></div><div><span>D、梯形</span><br><br><span>17</span><span>、一个圆柱与圆锥体的体积相等,圆柱的底面积是圆锥体的底面积的3倍,圆锥体的高与圆柱的高的比为(&nbsp;&nbsp; ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><br><br><span>A、3:1</span><span><br></span><span><br></span></div><div>B、1:3<br></div><div><span><br></span></div><div><span>C、9:1</span><span><br></span><span><br></span></div><div><span>D、1:9</span><br><br><span>18、下列图形中对称轴最多的是(&nbsp;&nbsp; ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><br><br><span>A、圆形</span><span><br></span><span><br></span></div><div><span>B、正方形</span><span><br></span><span><br></span></div><div><span>C、长方形</span><br><br><span>19、甲乙两地相距170千米,在地图上量得的距离是3.4厘米,这幅地图的比例尺是(&nbsp;&nbsp; ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><br><br><span>A、1:500</span><span><br></span><span><br></span></div><div><span>B、1:5000000</span><span><br></span><span><br></span></div><div><span>C、1:50000</span><br><br><span>20、一个长方形的面积是12平方厘米按1:4的比例尺放大后它的面积是(&nbsp;&nbsp; ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><br><br><span>A、48平方厘米</span><span><br></span><span><br></span></div><div><span>B、96平方厘米</span><span><br></span><span><br></span></div><div><span>C、192平方厘米</span><span><br></span><span><br></span></div><div><span>D、无法确定</span><br><br><strong><span>四、想清方法,我能算</span></strong><br><br><span>21、直接写出得数.</span><br><br><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024113420.png?m=0.20298313931840029"><br><br><span>22、用你喜欢的方法计算.</span></div><div><span><br></span></div><div><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024113456.png?m=0.7462475386674714"><br><br><span>23、解方程 &nbsp;&nbsp;&nbsp;</span><br><br><span>(1)x÷ 3/4</span><span>=5/6&nbsp;</span><br><br><span>(2)4:x=3:2.4. &nbsp;&nbsp;&nbsp;</span><br><br><span>24、求圆柱的体积(单位:cm) &nbsp;</span><br><br><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024113545.png?m=0.4423713978829942"><br><br><strong><span>五、操作题</span></strong><br><br><span>25、操作题</span></div><div><span><br></span></div><div><span>(i)把图A按2:1的比放大.</span><span><br></span><span><br></span></div><div><span>(ii)把图B绕O点顺时针旋转90°.</span><span><br></span><br><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024113629.png?m=0.4752607693279811"><br><br><strong><span>六、解决问题,我能行</span></strong><br><br><span>26、某校有男生630人,男、女生人数的比是7:8,这个学校女生有多少人? &nbsp;&nbsp;&nbsp;</span><br><br><span>27、在一幅比例尺是1:4000000的地图上,量得甲乙两地的距离是6厘米.一辆汽车以每小时80千米的速度从甲地开往乙地,需要几小时? &nbsp;&nbsp;&nbsp;</span><br><br><span>28、一个圆锥形小麦堆,底面周长为18.84米,高1.5米.如果每立方米小麦重0.75吨,这堆小麦约重多少吨?(得数保留整数) &nbsp;&nbsp;&nbsp;</span><br><br><span>29、给一间房子铺地,如果用边长6分米的方砖,需要80块.如果改用边长8分米的方砖,需要多少块? &nbsp;&nbsp;&nbsp;</span><br><br><span>30、把一段长20分米的圆柱形木头截成5段后,表面</span><span>积增加了80平方分米,那么这段圆木的体积是多少? &nbsp;&nbsp;&nbsp;</span><br><br><span>31、有一个高8厘米,容积50毫升的圆柱形容器,装满水,将一个圆柱形棒全部浸入容器水中,有水溢出.把棒从水中抽出</span><span>后,水的高度只有6厘米,求棒的体积. &nbsp;&nbsp;&nbsp;</span><br><br><br><div style="text-align: center;"><strong><font color="#38761d">答案解析部分</font></strong></div><br><span><strong>一、认真思考,我能填</strong></span><br><br><span>1、</span><span>【答案】</span><span>2;400;6.8</span></div><div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</span><span><br></span><span>【考点】</span><span>质量的单位换算,体积、容积进率及单位换算 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span>【解析】</span></div><div><span><br></span></div><div><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024113821.png?m=0.32580359898372313"><br><br><span>2、</span><span>【答案】</span><span>1:2=3:6或3:1=6:2 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span>【考点】</span><span>比例的意义和基本性质 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【解析】</span><span>【解答】解:因为1×6=2×3, &nbsp;所以1:2=3:6或3:1=6:2(答案不一);</span><span><br></span><span><br></span></div><div><span>故答案为:1:2=3:6或3:1=6:2(答案不一).</span><span><br></span><span><br></span></div><div><span>【分析】根据比例的性质“两外项的积等于两内项的积”,用1、2、3、6这四个数可以写出等式为1×6=2×3,再把此等式改写成比例式即可. &nbsp;&nbsp;&nbsp;</span><br><br><span>3、</span><span>【答案】</span><span>20;24;40;0.4 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【考点】</span><span>小数、分数和百分数之间的关系及其转化,比与分数、除法的关系 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span>【解析】</span><span>【解答】解: 8/20</span><span>=24÷60=2:5=40%=0.4. &nbsp;故答案为:20,24,40,0.4.</span></div><div><span><br></span><span>【分析】根据比与分数的关系2:5=2/5&nbsp;</span><span>,再根据分数的基本性质分子、分母都乘4就是 8/20</span><span>;根据比与除法的关系2:5=2÷5,再根据商不变的性质被除数、除数都乘12就是24÷60;2÷5=0.4;把0.4的小数点向右移动两位添上百分号就是40%.</span><br><br><span>4、</span><span>【答案】</span><span>50;50 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【考点】</span><span>百分数的加减乘除运算 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【解析】</span><span>【解答】</span></div><div><span><br></span></div><div><span>解: 40×(1+25%) &nbsp;=40×125%</span><span><br></span><span><br></span></div><div><span>=50(米)</span><span><br></span><span><br></span></div><div><span>答:比40米多25%是 50米.</span><span><br></span><span><br></span></div><div><span>40÷(1﹣20%)</span><span><br></span><span><br></span></div><div><span>=40÷80%</span><span><br></span><span><br></span></div><div>=50(米)<br></div><div><span><br></span></div><div><span>答:40米比 50米少20%.</span><span><br></span><span><br></span></div><div><span>故答案为:50,50.</span><span><br></span><span><br></span></div><div><span>【分析】(1)把40米看成单位“1”,用40米乘上(1+25%)就是要求的长度;(2)把要求的长度看成单位“1”,它的(1﹣20%)就是40米,根据分数除法的意义,用40米除以(1﹣20%)就是要求的长度.</span><br><span><br></span></div><div><span>5、</span><span>【答案】</span><span>5:8 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【考点】</span><span>求比值和化简比 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【解析】</span><span>【解答】解:1/4</span><span>:2/5&nbsp;</span><span>=(1/4&nbsp;</span>×<span>&nbsp;20</span><span>):(2/5&nbsp;</span>×<span>&nbsp;20</span><span>)=5:8. &nbsp;故填:5:8.</span><span><br></span><span><br></span></div><div><span>【分析】分数比(前后项都是分数)化简是把比的前后项同时乘上它们分母的最小公倍数,约分去掉分母,变成整数比如果整数比还不是最简比,还要按整数比的化简方法继续化简. &nbsp;&nbsp;&nbsp;</span><br><br><span>6、</span><span>【答案】</span><span>5:3;25:9 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【考点】</span><span>比的意义,圆、圆环的周长 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【解析】</span><span>【解答】解:设大圆的周长是5,小圆的周长是3,由圆的周长公式C=2</span><span>π</span><span>r,可知r=C÷(2</span><span>π</span><span>),那么大圆的半径是:5÷(2</span><span>π</span><span>)= 2.5/</span>π,</div><div><span><br></span></div><div><span>小圆的半径是:3÷(2</span><span>π</span><span>)= 1.5/</span>π,</div><div><span><br></span></div><div><span>则大圆和小圆半径的比为 2.5/</span>π:1.5/π =5:3;</div><div><span><br></span></div><div><span>由圆的面积公式S=</span><span>π</span><span>r</span><sup><span style=" vertical-align: super;">2</span></sup><span>,</span><span><br></span><span><br></span></div><div><span>可得大圆的面积是:</span><span>π</span><span>(5)</span><sup><span style=" vertical-align: super;">2</span></sup><span>=25</span><span>π</span><span>,</span><span><br></span><span><br></span></div><div><span>小圆的面积是:</span><span>π</span><span>(3)</span><sup><span style=" vertical-align: super;">2</span></sup><span>=9</span><span>π</span><span>,</span><span><br></span><span><br></span></div><div><span>所以大圆和小圆的面积比是:</span><span><br></span><span><br></span></div><div><span>25</span><span>π</span><span>:9</span><span>π</span><span>=25:9;</span><span><br></span><span><br></span></div><div><span>故答案为:5:3,25:9.</span><span><br></span><span><br></span></div><div><span>【分析】根据题意,可以假设大圆的周长是5,小圆的周长是3,由圆的周长公式C=2</span><span>π</span><span>r求出大小圆的半径,再根据圆的面积公式S=</span><span>π</span><span>r</span><sup><span style=" vertical-align: super;">2</span></sup><span>可以求出大小圆</span>的面积,再根据比的意义就可求出它们的半径的比和面积比.&nbsp; &nbsp;&nbsp;</div><div><br><span>7、</span><span>【答案】</span><span>反;正 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【考点】</span><span>正比例和反比例的意义 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【解析】</span><span>【解答】解:因为 </span><span>=c,所以b×c=a(一定),是乘积一定,b和c就成反比例; 因为 a/b</span><span>=c,所以a÷c=b(一定),是比值一定,a和c就成正比例.</span><span><br></span><span><br></span></div><div><span>故答案为:反,正.</span><span><br></span><span><br></span></div><div><span>【分析】判断两种相关联的量成什么比例,就看这两种量是对应的比值一定,还是对应的乘积一定,如果是比值一定,就成正比例,如果是乘积一定,就成反比例,据此解答即可. &nbsp;&nbsp;&nbsp;</span><br><br><span>8、</span><span>【答案】</span><span>9;27 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span><br></span></div><div><span>【考点】</span><span>圆锥的体积,圆柱的侧面积、表面积和体积 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span>【解析】</span><span>【解答】解:圆锥的体积是:18÷2=9(</span><span>立方分米), &nbsp;圆柱的体积是:9×3=27(立方分米),</span><span><br></span><span><br></span></div><div><span>答:圆锥的体积是9立方分米,圆柱的体积是27立方分米.</span><span><br></span><span>故答</span><span>案为:9;27.</span><span><br></span><span><br></span></div><div><span>【分析】等底等高的圆柱的体积是圆锥的体积的3倍,所以等底等高的圆锥的体积比圆柱的体积少2倍,由此即可解答. &nbsp;&nbsp;&nbsp;</span><br><br><span>9、</span><span>【答案】</span><span>1 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span>【考点】</span><span>图上距离与实际距离的换算(比例尺的应用) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span><br></span><span>【解析】</span><span>【解答】解:20÷ 20/1</span><span>=1(厘米), &nbsp;答:这个零件的实际长度是1厘米.</span></div><div><span><br></span><span>故答案为:1.</span><span><br></span><span><br></span></div><div><span>【分析】要求这个零件的实际长度是多少厘米,根据“图上距离÷比例尺=实际距离”,代入数值,计算即可. &nbsp;&nbsp;&nbsp;</span><br><br><span>10、</span><span>【答案】</span><span>1 &nbsp;</span></div><div><br></div><div>【考点】圆锥的体积&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<span><br></span></div><div><span><br></span></div><div><span>【解析】</span><span>【解答】解:</span></div><div><span><br></span></div><div><span>9.42×3÷(3.14×3</span><sup><span style=" vertical-align: super;">2</span></sup><span>)</span></div><div><span><br></span></div><div><span>=28.26÷28.26</span><span><br></span><span><br></span></div><div><span>=1(厘米),</span><span><br></span><span><br></span></div><div><span>答:这个圆锥的高是1厘米.</span><span><br></span><span><br></span></div><div>故答案为:1.<br>【分析】圆锥的体积= 1/3πr<sup><span style=" vertical-align: super;">2</span></sup>h,由此可得圆锥的高=体积×3÷(πr<sup><span style=" vertical-align: super;">2</span></sup>),代入数据即可计算出这个圆锥的高. &nbsp;&nbsp;&nbsp;<br><br><strong>二、仔细推敲,我能辨</strong>&nbsp; &nbsp;<br><br>11、【答案】错误 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】圆锥的体积,圆柱的侧面积、表面积和体积 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【解答】解:因为只有等底等高的圆锥的体积是圆柱体积的 1/3,所以在没有确定能否等底等高的前提条件下,圆锥体积是圆柱体积的 1/3,这种说法是错误的.</div><div><br></div><div>故答案为:错误.</div><div><br>【分析】只有等底等高的圆锥的体积是圆柱体积的 1/3,据此判断即可.</div><div><br>12、【答案】错误</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br>【考点】长方形的周长,长方形、正方形的面积 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【解答】解:可以举例证明,当长方形的周长是24厘米时:一种长是10厘米,宽是2厘米,面积是20平方厘米;</div><div><br>另一种长是8厘米,宽是4厘米,面积是32平方厘米;</div><div><br>很显然20平方厘米不等于32平方厘米.<br><br></div><div>所以说周长相等的两个长方形,面积也一定相等,这种说法是错误的.<br><br></div><div>故答案为:错误.<br><br></div><div>【分析】如果两个长方形的周长相等,长与宽相差越小面积就越大,当长和宽相等时(正方形)面积最大.由此解答. &nbsp;&nbsp;&nbsp;<br><br>13、【答案】正确 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】比例的意义和基本性质 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【解答】解:因为在比例里,两外项的积等于两内项的积, &nbsp;所以在比例里,两内项的积除以两外项的积,商等于1的说法正确.<br><br></div><div>故答案为:正确.<br><br></div><div>【分析】根据比例的性质“两外项的积等于两内项的积”,可知在比例里,两内项的积除以两外项的积,商等于1的说法是正确的. &nbsp;&nbsp;&nbsp;<br><br>14、【答案】错误 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】比例尺 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【解答】解:100米=10000厘米, &nbsp;这幅图的比例尺1:10000,所以题干的说法是错误的.<br><br></div><div>故答案为:错误.<br><br></div><div>【分析】根据比例尺的意义,即图上距离和实际距离的比,找准对应量,即可求出比例尺. &nbsp;&nbsp;&nbsp;<br><br>15、【答案】错误 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】比的意义 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【解答】解:</div><div>10:(10+90)</div><div><br></div><div>=10:100<br><br></div><div>=1:10<br><br></div><div>所以,农药与农药水的比是1:10,原题说法错误;<br><br></div><div>故答案为:错误.<br><br></div><div>【分析】把10克的农药溶入90克的水中,农药水为(10+90)克,由题意即可得出农药与农药水的比,然后化成最简整数比判断即可. &nbsp;&nbsp;&nbsp;<br><br><strong>三、反复比较,我能选</strong><br><br>16、【答案】B &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】圆锥的特征 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【解答】解:根据圆锥的特征可知:圆锥的侧面展开后是一个扇形; &nbsp;故选:B.<br><br></div><div>【分析】根据圆锥的特征:圆锥的侧面展开后是一个扇形,据此选择即可.&nbsp; &nbsp;<br><br>17、【答案】C &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】比的意义,圆锥的体积,圆柱的侧面积、表面积和体积 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【解答】解:</div><div><br></div><div><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024114941.png?m=0.4957206051933565">&nbsp;&nbsp;<br></div><div><br>18、【答案】A &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】确定轴对称图形的对称轴条数及位置 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【解答】解:据轴对称图形的特点和定义可知:正方形有四条对称轴,长方形有两条对称轴,圆形有无数条对称轴;</div><div><br></div><div>故应选:A.<br><br></div><div>【分析】依据轴对称图形的定义即可作答. &nbsp;&nbsp;&nbsp;<br><br>19、【答案】B&nbsp;</div><div>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br>【考点】比例尺 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【解答】解:170千米=17000000厘米,比例尺=3.4:17000000=1:5000000.</div><div><br>答:这张地图的比例尺为1:5000000.<br><br></div><div>故选:B.<br><br></div><div>【分析】根据比例尺=图上距离:实际距离,可直接求得这张地图的比例尺. &nbsp;&nbsp;&nbsp;<br><br>20、【答案】C&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br><br></div><div>【考点】图形的放大与缩小 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【解答】解:12×16=192(平方厘米);故选:C</div><div><br>【分析】一个长方形的面积是12平方厘米按1:4的比例尺放大后,它的长和宽都扩大到原来的4倍,即长×4,宽×4,由长方形的面积是长×宽,因此长方形的面积将放大4×4=16倍,原来的面积是12平方厘米,就可求得放大的后的面积.&nbsp;&nbsp;<br><br><strong>四、想清方法,我能算</strong>&nbsp;<br><br>21、【答案】解:</div><div><br></div><div><img src="//www.szxuexiao.com/uploadimages/2017/1024/2017102411550.png?m=0.07814925048571086"><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【考点】分数的加法和减法,小数的加法和减法 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【分析】根据分数和小数加减乘除法的计算方法进行计算.(1/4+1/8)×4根据乘法分配律进行简算. &nbsp;&nbsp;&nbsp;<br><br>22、【答案】解:</div><div><br></div><div><img src="//www.szxuexiao.com/uploadimages/2017/1024/20171024115640.png?m=0.033342308482703364"><br></div><div><br>【考点】分数的四则混合运算 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【分析】①根据加法交换律和结合律进行简算;②根据乘法分配律进行简算;③先算乘法,再算减法;④先算小括号里面的加法,再算除法,最后算减法. &nbsp;&nbsp;&nbsp;<br><br>23、【答案】(1)解:</div><div><br></div><div>x÷ 3/4=5/6</div><div><br></div><div>x÷ 3/4×3/4 = 5/6×3/4&nbsp;<br><br></div><div>x= 5/8;<br><br></div><div>(2)解:</div><div><br></div><div>4:x=3:2.4&nbsp; &nbsp;3x=4×2.4<br><br></div><div>3x÷3=9.6÷3<br><br></div><div>x=3.2 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】方程的解和解方程,解比例&nbsp;</div><div>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br>【解析】【分析】</div><div><br></div><div>(1)根据等式的性质,方程两边同时乘以 3/4求解;</div><div><br></div><div>(2)根据比例的基本性质,原式化成3x=4×2.4,再根据等式的性质,方程两边同时除以3求解. &nbsp;&nbsp;&nbsp;<br><br>24、【答案】解:3.14×(6÷2)<sup><span style=" vertical-align: super;">2</span></sup>×8 &nbsp;=3.14×9×8<br>=226.08(立方厘米);</div><div><br>答:这个圆柱的体积是226.08立方厘米 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【考点】圆柱的侧面积、表面积和体积</div><div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【分析】根据圆柱的体积公式:v=sh,把数据分别代入公式解答.</div><div><br><strong>五、操作题</strong><br><br>25、【答案】解:根据题干分析,画图如下: &nbsp;</div><div><br></div><div><img src="//www.szxuexiao.com/uploadimages/2017/1024/2017102412053.png?m=0.25862175096267115"><br></div><div><br>【考点】作旋转一定角度后的图形,图形的放大与缩小 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【分析】(i)按2:1的比画出平行四边形放大后的图形,先数出原平行四边形的底与高分别是3和2;则放大后底与高的长度分别是3×2=6、2×2=4;由此即可画出放大后的平行四边形;(ii)根据图形旋转的方法,先把与点O在一条直线上的旗杆,绕点O顺时针旋转90°后,再根据旗面的位置关系,把三角形旗面画出来,即可得出旋转后的图形. &nbsp;&nbsp;&nbsp;<br><br><strong>六、解决问题,我能行</strong>&nbsp;<br><br>26、【答案】解:630× 8/7=720(人);&nbsp;</div><div><br></div><div>答:女生有720人.</div><div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【考点】比的应用 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【分析】把“男、女生人数的比是7:8”理解为女生人数是男生人数的 8/7;把男生人数看作单位“1”,进而根据一个数乘分数的意义,用乘法解答即可. &nbsp;&nbsp;&nbsp;<br><br>27、【答案】解:6÷ 1/4000000=24000000(厘米) &nbsp;24000000厘米=240千米</div><div><br>240÷80=3(小时)<br><br></div><div>答:从甲地开往乙地,需要3小时 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【考点】比例尺应用题 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【分析】先求出甲、乙两地的实际距离,根据实际距离=图上距离÷比例尺即可求出;要求汽车从甲地开往乙地,需要几小时,就是用距离除以速度即可. &nbsp;&nbsp;&nbsp;<br><br>28、【答案】解:麦堆的体积:</div><div><br></div><div>1/3×3.14×(18.84÷3.14÷2)<sup><span style=" vertical-align: super;">2</span></sup>×1.5,<br>= 1/3×3.14×3<sup><span style=" vertical-align: super;">2</span></sup>×1.5,<br><br></div><div>=3.14×9×0.5,<br><br></div><div>=14.13(立方米),<br><br></div><div>小麦的重量:<br><br></div><div>14.13×0.75≈11(吨);<br><br></div><div>答:这堆小麦约重11吨 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】关于圆锥的应用题&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br></div><div><br></div><div>【解析】【分析】要求这堆小麦的重量,先求得麦堆的体积,麦堆的形状是圆锥形的,利用圆锥的体积计算公式求得体积,进一步再求小麦的重量,问题得解. &nbsp;&nbsp;&nbsp;<br><br>29、【答案】解:设改用边长8分米的方砖,需要x块,&nbsp;</div><div><br></div><div>8×8×x=6×6×80;<br><br></div><div>64x=2880,<br><br></div><div>x=45.<br><br></div><div>答:改用边长8分米的方砖,需要45块 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【考点】图形的密铺,长方形、正方形的面积 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【分析】房子的地面面积一定,方砖的面积与方砖的块数成反比,据此可列比例解答即可. &nbsp;&nbsp;&nbsp;<br><br>30、【答案】解:</div><div><br></div><div>2×(5﹣1)=8(个);</div><div><br></div><div>80÷8×20,<br><br></div><div>=10×20,<br><br></div><div>=200(立方分米);<br><br></div><div>答:这段圆木的体积是200立方分米 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【考点】关于圆柱的应用题 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【解析】【分析】由题意可知:把圆柱形木头截成5段,要锯5﹣1=4次,共增加(2×4)个底面;也就是说,增加的80平方分米是8个底面的面积,由此可求出一个底面的面积,进而可求出整个圆木的体积. &nbsp;&nbsp;&nbsp;<br><br>31、【答案】解:</div><div><br></div><div>50毫升=50立方厘米;</div><div><br></div><div>8厘米长的圆柱形棒的体积:<br><br></div><div>50÷8×(8﹣6)<br><br></div><div>=6.25×2<br><br></div><div>=12.5(立方厘米);<br><br></div><div>棒的体积=12.5×2=25(立方厘米);<br><br></div><div>答:棒的体积是25立方厘米 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br><br></div><div>【考点】探索某些实物体积的测量方法,圆柱的侧面积、表面积和体积 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>【解析】【分析】根据求不规则物体体积的方法,利用排水法,只要求出容器的底面积和把棒从水中抽出后,水面下降的高,用容器的底面积×水面下降的高=棒的体积的一半;这样问题就得到解决,由此列式解答.</div><div>&nbsp;&nbsp;<br></div>