设[img=132x26]1803a4a5597a440.png[/img],则[img=47x27]1803a4a561bbc64.png[/img]( ),其中[img=44x21]1803a4a569e78c7.png[/img]为正整数.
A: [img=140x39]1803a4a577b05cc.png[/img]
B: [img=140x39]1803a4a581527fe.png[/img]
C: [img=124x39]1803a4a58e11101.png[/img]
D: [img=124x39]1803a4a5966101e.png[/img]
A: [img=140x39]1803a4a577b05cc.png[/img]
B: [img=140x39]1803a4a581527fe.png[/img]
C: [img=124x39]1803a4a58e11101.png[/img]
D: [img=124x39]1803a4a5966101e.png[/img]
举一反三
- 设[img=77x19]1802e2aa5a4095f.jpg[/img]，则E(X)=4，D(X)=4/3.
- 已知随机变量X的分布函数为[img=136x49]1803b69024c8270.png[/img] ，则X的均值和方差分别为 A: E(X)=2, D(X)=4 B: E(X)=4, D(x)=2 C: [img=162x43]1803b6902cd8bfb.png[/img] D: [img=162x43]1803b69034d9ffd.png[/img]
- 设随机变量X~N(-3，[img=16x22]1803bbe3375949b.png[/img])，则D(X)=4 .
- Which of the following propositions is false,set A = {x,x is an integer and[img=60x23]1803a1c6eebb7a3.png[/img]} ? ( ) A: [img=113x25]1803a1c6f77ce06.png[/img] B: [img=139x25]1803a1c7001fe79.png[/img] C: [img=51x22]1803a1c70863f61.png[/img] D: {x|x is an integer and |x| 4}[img=33x22]1803a1c711a7c63.png[/img]
- Which of the following propositions is false,set A = {x,x is an integer and [img=60x23]1803a1c503ffa04.png[/img]} ? ( ) A: [img=113x25]1803a1c50cc3162.png[/img] B: [img=139x25]1803a1c514e60ea.png[/img] C: [img=51x22]1803a1c51dd52ef.png[/img] D: {x|x is an integer and |x| <4} [img=33x22]1803a1c525cf1bd.png[/img]