Given:
Given that sum of rupees 800 amounts to rupees 1280 in 5 years at certain rate.
Find:
we have to find the sum of amount to rupees 2400 in 5 years at the same rate.
Step-by-step explanation:
firstly, we will find the rate of interest by which sum of rupees 800 amounts to rupees 1280 in 5 year.
Principal (P) = 800
Amount (A) = 1280
Principal(P) + Simple Interest (I) = 1280
800 + I =1280
I = 1280 - 800
I = 480
Time (T) = 5 years
Rate of interest (R) = ?
Now we know I = PRT
480 = 800*R*5
R = 480/4000 = 0.12
By converting R from decimal to percentage
0.12*100 = 12%
Now we will find the sum of rupees, which becomes 2400 in 5 year with 12% rate of interest.
Let x be the principal, which amounts to 2400 in 5 year.
Therefore,
Simple interest (I) = x*(0.12)*5
I = 0.6x
Now, Amount after 5 year(A)=2400
Principal (P) + Simple interest (I) = 2400
x+ 0.6x = 2400
1.6x = 2400
x = 2400/1.6 =1500.
Therefore, Sum of rupees is 1500, which amounts to 2400 in 5 years at 12% interest rate.