Question

60persent of students passed an exam . If 5 more students were declared passed later on,the result would have been 70persent. How many students are there in the class?

Answer 1

let the number of students be x
60% passed

therefore, 60/100*x students passed
5 more were declared later.
so number of students passed = 60/100*x + 5
70% students passed
that is, 70/100*x students passed
therefore, 
70/100*x = 60/100*x + 5
70/100*x-60/100*x = 5
10/100*x = 5
1/10*x = 5
x = 5*10
x = 50

therefore, the number of students in the class = 50