a. This information is given to you.
b. We want to find
so we first transform
to the standard normal random variable
with mean 0 and s.d. 1 using
where
are the mean/s.d. of
. Now,
where
is the CDF for
.
c. The 76th percentile is the value of
such that
Transform
to
and apply the inverse CDF of
.