RRB NTPC 18 January 2017 Paper

(3) Let the number of boys be 2xand that of girls be x.
According to the question:
x + 2x = 135
3x = 135
x = 45
So, the number of girls = 45
And, number of boys = 90
Since, $\frac{1}{6}$of boys and $\frac{1}{3}$of girlfailed in examination. So, $\frac{5}{6}$of theboys and $\frac{2}{3}$of girls passed inexamination.
Passed $=\frac{\frac{5}{6}\times 90+\frac{2}{3}\times 45}{135}\times 100$$=\frac{75+30}{135}\times 100$$=77.78\%$