So I am struggling with a question in statistics following :
An investment broker reports that the yearly returns on common stocks are approximately normally distributed with a mean of 12,4% and a standard deviation of 20,6%. On the other hand, the firm reports that the yearly returns on tax-free municipal bonds are approximately normally distributed with a mean return of 5,2% and a standard deviation of 8,6% Find the probability that a randomly yearly selected :
c) Common stock will give more than a 10% return.
Formula : $P(0,01>b)=1-P(X\le b)$
$Z=0,10-12,40/20,60 = 0,597$
Which gives me 0,2743 on normal table and :
$1-0,2743 = 0,7257$
So this should in theory mean the probability of more than 10% revenue is 0,7257?
The next question is with a loss of at least 10% how should I compute that?