Question

A sum of money invested at compound intrest doubles itself in4yrs intrest being payable annually. In how much time will it be eight times. plzz explain​

Answer 1

Step-by-step explanation:

kindly kindly see the pic attached to this hope it will really help you

Answer 2

The formula for such questions of compound intrest is,

A=[P(1 + r/n)^nt] -P

Where A is Amount, P is Principle, r is Rate of Intrest, t is Time and n is number of times the intrest is compounded per t.

Let the principle here be x.

t is 1 year.

For 4 years, n1=4.

For x years, n2=8.

I am using a different formula to make it easier, n2=n1^(t2/t1)

Putting the values in it,

8=4^(x/4)

2^3=2^2(x/4)

Thus,

3=2(x/4)

12=2x

x=6

Thus the intrest will be 8 times in 6 years.

You can use the aforementioned formal as well.

4p=p(1+r/100)^4

Thus

4=(1+r/100)^4

For x years,

8=(1+r/100)^n

Which gives us again 6 years.