Trainees

[sairamGmat]

All trainees in a certain aviator training program must take both a written test and a flight test. If 70 percent of the trainees passed the written test, and 80 percent of the trainees passed the flight test, what percent of the trainees passed both tests?
(1) 10 percent of the trainees did not pass either test.
(2) 20 percent of the trainees passed only the flight test.

OA is D . I thought it is B. Not sure why it is OA..

[kvcpk]

All trainees in a certain aviator training program must take both a written test and a flight test. If 70 percent of the trainees passed the written test, and 80 percent of the trainees passed the flight test, what percent of the trainees passed both tests?
(1) 10 percent of the trainees did not pass either test.
(2) 20 percent of the trainees passed only the flight test.

OA is D . I thought it is B. Not sure why it is OA..

W=70
F=80

W and F = W+F- W or F
(1) 10 percent of the trainees did not pass either test.
W or F = 100-10 =90
90=70+80-W and F
W and F = 60
Therefore 60 percent passed both.

(2) 20 percent of the trainees passed only the flight test.
F=80
Only flight =20
Therefore both F and W is 60

pick D

[gmatmachoman]

Explanation by Praveen is very fine..