题目内容
从甲、乙两种玉米苗中各抽10株,分别测得它们的株高如下(单位:cm)
甲:25 41 40 37 22 14 19 39 21 42
乙:27 16 44 27 44 16 40 40 16 40
问:(1)哪种玉米的苗长得高?
(2)哪种玉米的苗长得齐?
甲:25 41 40 37 22 14 19 39 21 42
乙:27 16 44 27 44 16 40 40 16 40
问:(1)哪种玉米的苗长得高?
(2)哪种玉米的苗长得齐?
(1)乙种玉米的苗长得高(2)乙种玉米的苗长得高,甲种玉米的苗长得整齐
(1)甲=(25+41+40+37+22+14+19+39+21+42)=×300="30" (cm),
乙=(27+16+44+27+44+16+40+40+16+40)
=×310=31(cm).
∴甲<乙,即乙种玉米的苗长得高.
(2)=[(25-30)2+(41-30)2+(40-30)2+(37-30)2+(22-30)2+(14-30)2+(19-30)2+(39-30)2+(21-30)2+(42-30)2]
= (25+121+100+49+64+256+121+81+81+144)
=×1 042="104.2" (cm2),
=[(27-31)2×2+(16-31)2×3+(44-31)2×2+(40-31)2×3]
=×1 288="128.8" (cm2).
∴<.
即乙种玉米的苗长得高,甲种玉米的苗长得整齐.
乙=(27+16+44+27+44+16+40+40+16+40)
=×310=31(cm).
∴甲<乙,即乙种玉米的苗长得高.
(2)=[(25-30)2+(41-30)2+(40-30)2+(37-30)2+(22-30)2+(14-30)2+(19-30)2+(39-30)2+(21-30)2+(42-30)2]
= (25+121+100+49+64+256+121+81+81+144)
=×1 042="104.2" (cm2),
=[(27-31)2×2+(16-31)2×3+(44-31)2×2+(40-31)2×3]
=×1 288="128.8" (cm2).
∴<.
即乙种玉米的苗长得高,甲种玉米的苗长得整齐.
练习册系列答案
相关题目