Question

What sum of money invested at 7.5% p.a simple interest for 2 years produces twice as much interest as ₹9600 in 3 years and 6 months at 10% p.a simple interest ?

Answer 1

1st case given

P=9600

R =10%

T =3 years or7/2,years

Soln

SI = PXRXT/100

PUTTING THE GIVEN VALUES

SI =9600X7/2X10/100

=96X35=RS3360/-

NOW A/Q

NEW SI is 2 x 3360

=6720/-

Again for new SI

6720,=,PXRXT/100

6720=PX75/10X100X2

6720X100/15=P

THEREFOR P=44800/- IS THE REQUIRED ANS.

Answer 2

Answer:

First Case:

Principal (P1) = Rs 9600

Rate (R1) = 10%

Period = (T) = 3 years 6 months

= 3

2

1

years = 7 / 2 years

Simple interest = (P × R × T) / 100

= (9600 × 10 × 7) / (100 × 2)

We get,

= Rs 3360

Second case:

Simple interest = Rs 3360 × 2

= Rs 6720

Rate (R) = 7.5% p.a. and

Period (T) = 2 years

Therefore,

Principal = (S.I × 100) / (R × T)

= (6720 × 100) / (7.5 × 2)

= Rs (6720 × 100 × 10) / (75 × 2)

= 6720000 / 150

We get,

= Rs 44800