Let X and Y be indep. standard normal variables. Find:
a) $P(3X + 2Y \gt 5)$: This is just $1 - \phi(\frac{5}{\sqrt{13}})$ from the fact that the mean is 0, and the std. deviation is $\sqrt{13}$. Did you get 0.0838 as the probability for this one?
b) $P(Min(X,Y) \lt 1)$: This is equal to $P(X \lt 1 or Y \lt 1) = 2P(X\lt 1) - P(X^Y \lt 1) = 2(0.84) - (0.84)^2$, right?
c) $P(\mid min(X,Y)\mid < 1) = P(-1 \lt min(X,Y) \lt 1) = 2*0.68^2 - (0.68)^2$ ?
d) $P(Min(X,Y) \gt max(X,Y) - 1)$
Did you get the answer to be 0.7794?