设随机变量X服从参数为2的泊松分布，则D(9—2X)=（）。A1B4C5D8-新东方在线职业题库

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设随机变量X服从参数为2的泊松分布，则D(9—2X)=（）。

A

1

B

4

C

5

D

8

常见随机变量的方差

若X服从泊松分布，则D（X）=2，D(9—2X)=4D（X）=8。

多做几道

A

B

C

D

1

A

B

C

D

A

B

C

2

D

4

A

1

B

3

C

4

D

2

A

6

B

7

C

8

D

9

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