Question

at what rate percent will a sum of 4000 yield 1324 as compound intrest in 3 year

Answer 1

C.I = 1324
P = 4000
A = P + C.I = 5324
A = P[(1 + r/100)^n
5324 = 4000[(1 + r/100)]^3
5324/4000 = [(1 + r/100)]^3
1331/1000 = [(1 + r/100)]^3 ....(L.H.S was divided by '4')
(11/10)^3 = [(1 + r/100)]^3.....(11^3=1331, 10^3 = 1000)
On taking cube root of lhs & rhs
11/10 = 1 + r/100
r/100 = 11/10 - 1 = 11-10/10 = 1/10
r = 10%
Rate = 10%.
Hope it helps.