400 students took a mock test: 60% of the boys and 80% of the girls cleared the cut off in the test. If the total percentage of students clearing the cut off in the test is 65%, then how many girls appeared in the test?

Correct option is A

Let's assume there were b boys and g girls in the test.
According To question:
the total number of students who cleared the cut off = (60/100)b + (80/100)g = 0.65 * 400
the total number of students who took the test = b + g = 400
⇒ b = 400 - g
Substituting this value of b in the first equation:
(60/100)(400 - g) + (80/100)g = 0.65 * 400
Expanding and simplifying the equation:
240 - 0.6g + 0.8g = 260
0.2g = 20
g = 100
So, 100 girls appeared in the test.