Question

the simple interest on a certain sum for 5 years @ 8% p.a. is Rs.272/- less than the simple interest on the same sum for 6 years at 12% p.a. Find the sum

Answer 1

Let the sum be x.
SI for 5 years at 8% p.a. = x*5*8/100.= 2x/5
SI for 6 years at 12% p.a. = x*6*12/100 = 18x/25.
Now,
As per the question,
18x/25 -2x/5 = 272
(18x-10x)/25 = 272
x = 272*25/8 = 34*25 =850.
Thus, the sum is Rs 850.

Answer 2

Let the sum be ₹x

First case:

P=₹x, R= 12%p.a., T=5 yrs

S.I= ₹PRT/100

=₹x*8*5/100

=₹40/100

Second case:

P=₹x, R=12%p.a., T=6yrs

S.I=₹PRT/100

=₹X*12*6/100

=₹72x/100

Given:

72x/100-40x/100

=272

=32x/100

=272

X = 272*100/32

= ₹850