the average numbers of hours a cat sleep is approximately normally distributed with a mean of 15 hours and a standard deviation of 1.7 hours; what percentage of cats sleep between 13 and 18 hours

Answer 1

z = (13-15)/1.7
z = -1.18
z = (18-15)/1.7
z = 1.76

p (-1.18 < z < 1.76) = 0.9608-0.1190 = 0.8418
84.18%