Question

甲、乙兩棉農(nóng)，統(tǒng)計(jì)連續(xù)五年的單位面積產(chǎn)量(kg/畝)如下表:

棉農(nóng)甲	68	72	70	69	71
棉農(nóng)乙	69	71	68	68	69

則平均產(chǎn)量較高與產(chǎn)量較穩(wěn)定的分別是

A.棉農(nóng)甲，棉農(nóng)甲                                                 B.棉農(nóng)甲，棉農(nóng)乙

C.棉農(nóng)乙，棉農(nóng)甲                                                 D.棉農(nóng)乙，棉農(nóng)乙

Answer 1

B

解析:

本題考查樣本的均值與方差.

_甲=(68+72+70+69+71)=70,

_乙= (69+71+68+68+69)=69;

s_甲²=［(68－70)²+(72－70)²+(70－70)²+(69－70)²+(71－70)²］=2,

s_乙²=［(69－69)²+(71－69)²+(68－69)²+(68－69)²+(69－69)²］=1.2.