Thread: Z-Score Question

Q: Suppose that X ~ N(-7,14). Find the value of x for which P(|X+7|<x)=0.44

Work so far:
-x < X + 7 < x
-x-7 < X < x-7

Hey xxlvh.

Remember that (X-mu)/sigma ~ N(0,1) if X is Normal(mu,sigma^2) so try getting it into P(a < Z < b) form and then using the tables to get the values for a and b [Note that the Normal distribution is symmetric around 0 for a standardized normal so P(Z < -a) = P(Z > a) for a >= 0]