Question

Pramod is 15 years younger than his sister after 5 years he will be half his sister age find the present age

Answer 1

P = Pramod age

S = Sister age


Difference of their age now = 15 yr

So :

P = S - 15


After 5 years Pramod will be 5 years older, and sister will be 5 years older.

Ratio of their age will be :

( P + 5 ) / ( S + 5 ) = 1 / 2


P = S - 15 so :

( S - 15 + 5) / ( S + 5 ) = 1 / 2

( S - 10 ) / ( S + 5 ) = 1 / 2


Now you must solve equation :

( S - 10 ) / ( S + 5 ) = 1 / 2 Multiply both sides by 2

2 ( S - 10 ) / ( S + 5 ) = 1

( 2 S - 20 ) / ( S + 5 ) = 1 Multiply both sides by S + 5

2 S - 20 = S + 5 Subtract S to both sides

2 S - 20 - S = S + 5 - S

S - 20 = 5 Add 20 to both sides

S - 20 + 20 = 5 + 20

S = 25

P = S - 15 = 10


The present age :

Pramod 10 yr

Sister 25 yr


Proof :

After 5 years Pramod will be 10 + 5 = 15 yr old.

Sister will be 25 + 5 = 30 yr old.


15 / 30 = 1 / 2