What salary marks the start of the upper 20% ?

Question

Given that the average monthly salary of nurses in the Philippines is 23,000

php with a standard deviation of 1,000 php. What salary marks the start of the upper 20% ?

Answer 1

upper 20% percent is 80th percentile.

z-score associated with 80th percentile is 0.84

standardized z-score z = (x - mean)/standard deviation, where x = salary

0.84 = (x - 23000)/1000

x = 23840