OA is A

sairamGmat wrote:In an office, 40 percent of the workers have at least 5 years of service, and a total of 16 workers have at least 10 years of service. If 90 percent of the workers have fewer than 10 years of service, how many of the workers have at least 5 but fewer than 10 years of service?

(A) 48
(B) 64
(C) 50
(D) 144
(E) 160

Let total workers be x.
Given :
Workers with at least 5 yrs experience = 0.4x
Workers with at least 10 yrs experience = 16
Workers with fewer than 10 yrs experience = 0.9x
This means, workers with at least 10 yrs experience = x - 0.9x = 0.1x
Solve for x, 0.1x = 16...x = 160
So total workers = 160
Workers with at least 5 yrs experience = 0.4x = 160 * 0.4x = 64.
Workers with more than 5 but less than 10 yrs experience = 64 - 16 = 48 (A)

key thing here is finding the total employee (160)