Question

A sum of money trebles itself in 6 years at a certain
rate of interest. In how many years will it become
four times itself at the same rate of interest?

please tell the method so the answer is 7years​

Answer 1

Step-by-step explanation:

method 1

A SUM ON SIMPLE INTEREST BECOMES 3 TIMES IN 6 YEARS.

i.e IT EARNS 2 TIMES INTEREST IN 6 YEARS.

IF IT HAS TO BECOME 9 TIMES IT SHOULD EARN 8 TIMES INTEREST

THAT IS POSSIBLE IN 24 YEARS

ANSWER : 24 YEARS

method 2

x becomes 3*x in 6 years. x+2*x=3*x.

x becomes 2*x in 3 years. x+1*x=2*x.

We need x+8*x = 9*x.

For 1*x of S.I, it takes 3 years.

For 8*x of S.I., it will take 8*3=24 years.