Answer:
a) 18 cm
b) 18
c) 3
The Earl's height is unusual because the z score does not lies in the given range of usual i.e -2 and 2
Explanation:
Given:
Mean height, μ = 174 cm
Standard deviation = 6 cm
height of Earl, x = 192 cm
a) The positive difference between Earl height and the mean = x - μ
= 192 - 174 = 18 cm
b) standard deviations is 18
c) Now,
the z score is calculated as:

or

or
z = 3
The Earl's height is unusual because the z score does not lies in the given range of usual i.e -2 and 2