Question

if an amount gets double in 6 years at simple interest,then in how many years will it take to become 4 times?

Answer 1

Let the principal be m
A/q to this amount will be 2m
And Amount -Principal=Simple interest{2m-m=m}
Rate =r
Time =6years
SI = P×R×T/100

m=m×r×6/100(m will be canceled)
Then r =100/6percent

Now the Amount is 4times of principal(m)
Then SI will be 3m
Time =t
now putting in equation
SI=P×R×T/100
3m=m×100×t/600(6 will multiply by 100 in denominator)
3=100t/600(m will be canceled)
3=t/6
t=18 years