Question

The difference between the compound interest and simple interest on a certain principal at 10% p.a for 3yrs is rupees 31. Find the principal.​

Answer 1

CI - SI = 31 Rs

CI = P( 1 + R/100)^T - P

SI = PRT/100

CI- SI= P(1+R/100)^T - P - PRT/100

So,

P{ ( 1+1/10)^3 - 1 - 10×3/100} = 31

P{ 1331/1000 -1 - 3/10} = 31

P{ ( 1331-1000-300)/1000} = 31

P{ 31/1000} = 31

P = 1000