Question

A sum of money 8/5 of itself in 5years at a certain rate of simple interest.Find the rate of interest?

Answer 1

let sum be'x'

8x/5= S.I

Time=5years

Rate=R

since, S.I =P×R×T/100

THEREFORE,

8x/5=x×5×R/100

since 'x' will cancel

R=8×100/5×5(cross multiply terms)

R=32%ans.

Answer 2

Answer:

12%

Step-by-step explanation:

Let Principal be p .

p with SI for 5 years (amount in 5 years) = 8p/5

SI for 5 years = Amount - Principal

                      = 8p/5 - p

                      = 8p/5 - 5p/5

                      = 3p/ 5

SI for 1 year    = (3p/5 ) / 5

                       =(3p/5) * (1/5)

                       = 3p/25

x% of p            = 3/25

x/100 * p          = 3/25

x                       = (3/25) / p * 100

x                       = (3/25) * (1/p) * 100

x                       = 12 %

Rate                 = 12%

... Hope this helps !