Question

Out of 300 examinees of a school the ratio of successful to unsuccessful students is 5:1. How many more students have to be successful so that the ratio of successful to unsuccessful students becomes 9:1

Answer 1

200 more students have to be successful to become 9:1

Answer 2

Total = 300
the ratio is 5:1 implies that the real number of students will be a multiple of 5 and 1.
=> successful = 5x
     unsuccessful = x
=> total = 5x+x=6x
but total = 300
=> 6x=300
=> x = 50.
=> successful students = 5*50= 250
and unsuccessful = 50.
now same as for 2nd case.
 9y+y=300
=>10y=300
=>y=30
=> successful in 2nd case = 9*30=270
initially successful were 250 and now 270
=> more successful= 270-250=20