Conditional normal distribution

[Gauss M.D.]

Homework Statement

We have two normally distributed random variables:

A = N(129, 29.4)
B = N(86, 24.0)

What is the probability A is atleast twice the size of B?

The Attempt at a Solution

P(A > 2B | B = b) or something? I think we are supposed to use the CLT somehow but I don't know how when it's conditional...

 

[Ray Vickson]

Homework Statement

We have two normally distributed random variables:

A = N(129, 29.4)
B = N(86, 24.0)

What is the probability A is atleast twice the size of B?

The Attempt at a Solution

P(A > 2B | B = b) or something? I think we are supposed to use the CLT somehow but I don't know how when it's conditional...

In the notation N(a,b), is b the variance or the standard deviation? I have seen both conventions used, so you need to tell us which one you mean. Also: are A and B independent?---you need to tell us that, too.

 

[Gauss M.D.]

b is the stdev. A and B are independent. Sorry!