Question

the simple interest on a certain sum of money for 2 years at 10% per annum is 1,600 the first question find sum. second question amount due after 3 years and above sum of the same interest and compound annually answer for the first q: principal equal to 8000 and the second question amount is equal to 10648 is the answer correct or wrong

Answer 1

n = 2 years, r = 10%,  p= 1600
SI = pnr/100
     =1600 x 2 x 10 / 100
     = rs. 320
Amount = P + SI
             = 1600 + 320
             = rs.1920 

for 3 years
SI = 1600 x 3 x 10 / 100
    = rs. 480
Amount due at 3 years = 1600 + 480 = rs. 2080
Compound interest-> Amount  = p(1 + r/100)^n
           Amount         = 8000 ( 1 + 10/100)^2
                                = 8000 x 1.1 x 1.1
                                = 8000 x 1.21
                                =rs. 9680
so, C.I                     = 9680 - 8000 = 1680
The given answer (Rs. 10648) is wrong because we got Rs.9680