Question

A sum of money doubles in 10 years. it will treble at how many years at the same rate of simple interest

Answer 1

THE SUM WILL TRIPLE IN 20 YEARS

Answer 2

let first find the rate of interest

let the principal be 100

In 10 years the amount is 200

interest=amount-principal

=200-100

=100

so by the formula

S. I. =PNR/100

100=100×10×R/100

R=100/10

R=10

rate of interest is 10 p. c. p. a

short method to find rate is

rate=principal/time

only in case of such example

now we have

principal=100

rate=10

it will tribals means amount is 300

s. I =300-100=200

200=100×10×N/100

N=200/10

N=20 years