Question

find the rate percent per annum,if rs 4000 amount to rs 5324 in 1.5 years,interest being compounded half yearly.

Answer 1

Principal(P)  = Rs 4000

Rate of Interest(r )  = 10%

Time = 2.5 years

Here first we take n = 2 years.

A = P( 1 + r /100)n  Where  A = Amount  and n = number of years

A = 4000 (11/10)2

A = 4000 ( 121 / 100 )

A = Rs 4840

The Amount after two years = Rs 4840

Now Principal = Rs 4840

Simple interest for last ½ year is = PRT/100  =  (4840 × 10 × 1 / 2) / 100 = Rs.242

Amount after 2 ½ year =  Rs 4840 +  Rs 242 = Rs 5082

C.I = A - P

C.I = Rs 5082 - Rs 4000 = Rs1082

∴ The compound interest is Rs 1082.