If X and Y are any two independent continuous random variables whose probability density is [img=41x25]1803dc1d154ea64.png[/img] and [img=38x26]1803dc1d1dd7772.png[/img],and whose distribution function is [img=47x25]1803dc1d26f6f50.png[/img] and [img=42x25]1803dc1d300d282.png[/img],then [img=47x25]1803dc1d26f6f50.png[/img] + [img=42x25]1803dc1d300d282.png[/img] must be the distribution function of a random variable.
举一反三
- 已知二维随机变量(X,Y)的联合分布函数为F(x,y)，那么F(+∞,y)= A: 0 B: 1 C: [img=45x25]180348de6a9bd5d.png[/img] D: [img=42x25]180348de72d76d4.png[/img]
- 设随机变量X的概率密度为f(x)，则f(x)一定满足( ). A: 0≤f(x)≤1 B: [img=183x53]1803b451bb3373a.png[/img] C: [img=133x51]1803b451c807078.png[/img] D: f(+∞)=1
- Let [img=47x25]1803a319caed5c0.png[/img] be the uniformly distributed within the unit circle, and the the joint probability density function be [img=501x61]1803a319d67d32e.png[/img]Then the marginal distribution of X in [img=47x25]1803a319caed5c0.png[/img] is also the uniform distribution.
- 设随机变量X服从均值为2的指数分布，X的分布函数为F(x)，数学期望为E(X)，方差为D(X)，则以下结果正确的是 A: [img=128x28]1802d3b369ab5fe.png[/img] B: D(X)=4 C: P(X<2︱X>1)=F(1) D: P(X>2︱X>1)= F(1) E: [img=112x27]1802d3b372fb534.png[/img] F: D(X)=E(X) G: P(X≤2︱X>1)= F(2) H: [img=82x27]1802d3b37bbbf05.png[/img]
- 设随机变量X服从均值为2的指数分布，X的分布函数为F(x)，数学期望为E(X)，方差为D(X)，则以下结果正确的是 A: [img=128x28]18034b986fbc78a.png[/img] B: D(X)=4 C: P(X<2︱X>1)=F(1) D: P(X>2︱X>1)= F(1) E: [img=112x27]18034b98781508a.png[/img] F: D(X)=E(X) G: P(X≤2︱X>1)= F(2) H: [img=82x27]18034b9880d080a.png[/img]