A certain sum amounts to 35916 in 3 years and to 36960 in 5 years at simple interest.
Find the sum and the rate per cent per annum.
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Class 11
>>Applied Mathematics
>>Basics of financial mathematics
>>Accumulation with simple and compound interest
>>A certain sum amounts to 79...
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A certain sum amounts to 798.60 after 3 years and 878.46 after 4 years. Find the interest rate and the sum.
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Solution
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It is given that
Amount after 3 years = 798.60
Amount after 4 years = 878.46
So the difference = 878.46 - 798.60 = 79.86
Here 79.86 is the interest of 798.60 for 1 year.
We know that
Rate = (SI×100)/(P×t)
Substituting the values
=(79.86×100)/(798.60×1)
Multiply and divide by 100
=(7986×100×100)/(79860×100×1)
=10%
Here
A= P(1+r/100)
n
It can be written as
P=A÷(1+r/100)
n
Substituting the values
P= 798.60÷(1+10/100)
3
By further calculation
P=79860/100×10/11×10/11×10/11
P=600