Question

the compound interest on a certain sum for 2 years at 12% per annum is Rs 3816.The simple interest on the same sum for double the time and same rate of percent per annum is​

Answer 1

Answer:

Hey mate here is your answer

Step-by-step explanation:

We know, CI = A - P [where A = Capital+Interest and P = Principal]

CI = P(1+r/100)^n - P [ r = rate of interest and n = no. of years]

Or, 525 = P[(1+10/100)^2 - 1]

Or, 525 = P[(1+1/10)^2 -1]

Or, 525 = P[(121/100) - 1]

Or, 525 = P*21/100

Or, P = 2500

For SI, P = 2500, n = 2*2 = 4, r = 10/2 = 5

We know, SI = Pnr/100

Or, SI = 2500*4*5/100 = 500

Answer 2

Step-by-step explanation:

C.I = P (1+R/100)^ n - P

3816 = P( 1+ 12 / 100)^2 - P

3816 = P ( 1 + 3 / 25)^2 -P. [ 12/100 = 3/25 ]

3816 = P ( 28/25)^2 -P. [ 1+ 3/ 25 = 28/25 ]

3816 = P [ (28/25 ) ^2 - 1 ]

3816 = P [ ( 28/25 + 1 ) ( 28/25 - 1 ) ]

28/25^2 - 1

= 28/25^2 - 1^2

using property

a^2 - b^2 = ( a + b) ( a - b )

3816 = P × 53/25 × 3/25

3816 = P × 159/ 625

3816 × 625 = P ×159

625× 3816/159= P

P = 625 ×24

P = 15000₹

S.I when time is doubled

S.I = ( P× R×T) / 100

S.I = ( 15000 × 12× 4 ) / 100

S.I = 150 × 12 × 4

S.I = 7200 ₹