问题 解答题

为考察甲、乙两种农作物的长势,分别从中抽取了10株苗,测得苗高如下(单位:cm):

甲:9,10,11,12,7,13,10,8,12,8;

乙:8,13,12,11,10,12,7,7,9,11.

如果你也参加了这次考察,请你经过计算后回答如下问题:

(1)哪种农作物的10株苗长的比较高?

(2)哪种农作的10株苗长的比较整齐?

答案

(1)∵

.
x
=
1
10
(9+10+11+…+8)=10,

.
x
=
1
10
(8+13+12+…+11)=10,

.
x
=
.
x
,即两种农作物的10株苗的平均高度相同.

(2)∵

.
x
=
.
x
=10,
S2甲
=
1
10
[(9-10)2+(10-10)2-(11-10)2+…+(8-10)2]=3.6

S2乙
=
1
10
[(8-10)2+(13-10)2-(12-10)2+…+(11-10)2]=4.2,

∴S2<S2

因此,甲种农作物的10株苗长的比较整齐.题21考查统计初步知识的应用,要分清各种统计量所体现数据特征,考查农作物比较高应用平均数分析,考查农作物比较整齐应用方差分析.

阅读理解

Canada geese are large blue and white birds .When autumn arrives ,they have to fly south where the weather is warmer .The winters are so cold in Canada that the birds will die if they stay there .

Last spring ,Bill Lishman found sixteen young Canada geese on his farm “They had lost their parents , ”Bill thought . “These young birds won’t know what to do in the autumn .

Bill had a small plane and he decided to teach the birds to follow him .All through the summer ,he went on short trips in his plane and the young geese flew after him .”

When the cold weather arrived in autumn ,Bill flew to Virginia in the United States ,600 miles south from his home in Canada .The geese follwed him all the way .Bill flew to Virginia and returned home .

This spring ,Bill was waiting for the birds to come back .They didn’t arrive ,so Bill flew to Virginia to get them .He looked for them for two weeks but he couldn’t find them .

When he arrived back home ,Bill found the geese waiting for him .Then had found the way home without him !

小题1: Canda geese have to flly south______.

A.in spring

B.before autumn

C.in the winter

D.after summer小题2:The young birds_____,so they could follow Bill to Virginia .

A.were well trained

B.went on trips in Bill’s plane

C.liked Bill

D.lost their parents小题3:Bill took the birds to virginia because ______.

A.it’s warmer there

B.it’s 600 miles away from his home

C.he wanted the birds to fly after him

D.it’s a beautiful place in the United States小题4:The birds returned to Bill’s home_______.

A.in Bill’s plane

B.by themselves

C.in the winter

D.in the autumn小题5:.From the passage we can know that Bill _____.

A.likes the birds very much

B.in an American bird-lover

C.stayed in Virginia with the birds

D.taught the birds to fly

单项选择题