Question

A sum doubles itself in 6 years at si in how many years will it become 6 times at same rate

Answer 1

I think this would help you my friend..

Let x % be the simple interest per annum on Principal amount(P) you deposited.
After 1 year your money will become P + x% P.
After 2 year your money will become P + x%P + x% P.
Similarly, After 6 years your money will become P + 6 (x% P).
Now According to Question, this amount after 6 years is 2 times the amount you deposited i.e P.
Mathematically it can be expressed as,
2P = P + 6 (x% P) ……………(i)
From here, x = 100/6.
Now let’s assume that after n years, your amount gets 4 times the amount you deposited i.e P.
Mathematically it can be expressed as,
4P = P + n (1/6 P) { Since x = 100/6, Therefore x% = 1/6} ………… (ii)
From equation (ii),
n = 18 years.
Therefore, this means that if you want to Quadruple your deposited amount with a simple interest of 1/6 % per annum. You have to wait for 18 years.


Keep Learning!!!!!

Answer 2

It Is as simple as this If it took 6 years to make the sum double which means x*2=6 by this we could divide 2/6 we get 3. But now we should multiply 3 with how much do we want the sum to increase to in this case 6 times therefore we get 3*6=18 years