Question

of the 132 examinees of a certain school, the ratio of sucessful to unsucessful students is 9:2. if 4 more students passed, what would have been the ratio of sucessful to unsucessful students?

Answer 1

Let the students who are successful be 'x' and who are unsuccessful be 'y'

Now according to the question,

x+y = 132  

and x/y = 9/2

⇒ x = 9y/2

⇒ 9y/2 + y =132 (substituting 'x' from the first equation)

⇒ (9y + 2y)/2 = 132

⇒ 9y + 2y = 132 × 2 = 264

⇒ 11y = 264

∴ y = 264/11 = 24

Now,    x +y =132

⇒ x = 132 - y = 132 - 24 = 108

Given that 4 more students are successful, ⇒ x +4 and y -4

∴ (x+4)/(Y-4) = (108+4)/(24 - 4) = 112/20 = 28/5

∴ New ratio is 28:5