Question

The shelf life of milk is normally distributed with a mean of 54 days and a standard deviation of 3 days. Approximately what percentage of milk would last more than 60 days

Answer 1

X=60 days.
Z-score=(X-mean)/standard deviation
=(60-54)/3=2
Look up Z=2 in the normal distribution to get the percentage of milk that lasts LESS than 60 days
P(Z<=60)=0.9772449, so
P(Z>60)=1-P(Z<=60)
=1-0.9772449
=0.02275013, or approximately 2.275%