每一吨铸铁成本(元)倚铸件废品率(%)变动的回归方程为:yc=56+8x,这意味着(

题型:单项选择题

问题:

每一吨铸铁成本(元)倚铸件废品率(%)变动的回归方程为:yc=56+8x,这意味着()。

A.废品率每增加1%,成本每吨增加64元

B.废品率每增加1%,成本每吨增加8%

C.废品率每增加1%,成本每吨增加8元

D.废品率每增加1%,则每吨成本为56元

考点:统计学统计学原理统计学原理题库
题型:单项选择题

阅读短文,选择正确的答案。

      Sam and Lisa are from Australia. Sam is twelve and Lisa is six. They came to Canada this summer because

their father found a job (工作) here. They live in a big apartment. There are three bedrooms, a living room, two

bathrooms and a kitchen. Sam and Lisa usually go to school by bus from Monday to Friday. This winter is very

cold and snowy. It always snows. They like snow and they never saw it before. They usually put on their hats,

mittens and scarfs and go out to play in the snow. They like to make a snowman and snowballs. Sometimes they

skate on the ice or ski on the snow. Now, Christmas is coming. They have no classes and their father will be at

home, too. It's a very, very special Christmas for them because it's summer in Australia, but in Canada it's

winter with white snow and a lot of ice. They are going to take some pictures and send them to their friends in

Australia.

1. Sam and Lisa are from _____________.

A. China

B. Canada

C. Australia

D. America

2. Sam and Lisa go to school _____________.

A. everyday

B. by bicycle

C. by cab

D. by bus

3. Which season is it now in Canada?

A. Winter.

B. Summer.

C. Spring.

D. Fall.

4. Do they go to school at Christmas?

A. Yes, they do.

B. No, they aren't.

C. Yes, they don't.

D. No, they don't.

5. When it's summer in Australia, it's _____________ in Canada.

A. winter

B. spring

C. summer

D. fall

题型:单项选择题

做匀加速直线运动的物体初速度为2 m/s,经过一段时间t后速度变为6 m/s,则时刻速度为

A.由于t未知,无法确定时刻的速度

B.由于加速度a及时间t未知,无法确定时刻的速度

C.5 m/s

D.4 m/s

题型:单项选择题

关于地球同步卫星,下列说法中正确的是(   )

A.由于它相对地球静止,所以它处于平衡状态

B.它的加速度一定小于9.8m/

C.它的速度小于7.9km/s

D.它的周期为一天,且轨道平面与赤道平面重合

题型:单项选择题

特定穴中,多用于急救的是()。

A.原穴

B.郄穴

C.络穴

D.井穴

E.募穴

题型:单项选择题

铂钻比色法测定水的色度时,测定结果以与水样色度最接近的标准溶液的色度表示,在0~40度范围内,准确到()度,40~70度范围内,准确到()度。

A.5,5

B.5,10

C.5,15

D.10,15

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