下图表示了室温时某气体分子按速率的分布，υ[img=5x18]1803df1c1225a36.jpg[/img]为室温时气体分子的最可几速率，而[img=9x11]1803df1c1b11e87.jpg[/img][img=5x18]1803df1c239d007.jpg[/img]表示在速率υ[img=5x18]1803df1c239d007.jpg[/img]附近单位速率区间内的气体分子数，若该气体的温度降低，则[img=16x16]1803df1c34c141f.jpg[/img]和υ[img=5x18]1803df1c239d007.jpg[/img]将如何变化( )。[img=388x285]1803df1c47164c6.jpg[/img]
A: υ[img=5x18]1803df1c50659d1.jpg[/img]变小而[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]保持不变
B: υ[img=5x18]1803df1c50659d1.jpg[/img]和[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]均变小
C: υ[img=5x18]1803df1c50659d1.jpg[/img]变小而[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]变大
D: υ[img=5x18]1803df1c50659d1.jpg[/img]保持不变而[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]变大
A: υ[img=5x18]1803df1c50659d1.jpg[/img]变小而[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]保持不变
B: υ[img=5x18]1803df1c50659d1.jpg[/img]和[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]均变小
C: υ[img=5x18]1803df1c50659d1.jpg[/img]变小而[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]变大
D: υ[img=5x18]1803df1c50659d1.jpg[/img]保持不变而[img=9x11]1803df1c58c4df6.jpg[/img][img=5x18]1803df1c50659d1.jpg[/img]变大
举一反三
- 卡方（[img=19x26]18038dc17708105.png[/img]）检验在（ ）的时候，须作连续性矫正。 A: 自由度df=∞ B: 自由度df=1 C: 自由度df=5 D: 自由度df=100
- 要求方程[img=69x27]1802e4da216c9dd.png[/img]的解，应使用命令 A: dsolve('Df=x^2') B: dsolve('Df==x^2') C: dsolve('Df=x^2',x) D: dsolve('Df==x^2',x)
- 设随机变量X的概率密度为[img=157x51]1803b4519b2ecc0.png[/img]则方差D(X)=( ). A: 1/3 B: 1/6 C: 1/9 D: 1/18
- 设连续型随机变量X 的概率密度函数为[img=177x53]1803be44df722bd.png[/img],则 D(X)= . A: 1/3 B: 1/6 C: 1/9 D: 1/18
- X为随机变量，E(X)=-1,D(X)=3,则[img=105x27]17de66c4ef75d99.png[/img] A: 18 B: 9 C: 30 D: 32