Question

A man opened a recurring deposit account in a bank and deposited Rs.2000 per month for 2 years. If he receives Rs.50500 at the time of maturity, find the rate of interest per annum given by the bank​

Answer 1

Answer:

P=Rs.2000

R=10%

M.V=Rs.83100

I=P×

2×12

n(n+1)

×

100

R

∴I=25×

24

n(n+1)

×

100

10

=

3

25(n

2

+n)

MV=P×n+I

⇒83100=(2000×n)+

3

25

n

2

+

3

25

n

⇒83100=

3

6000n+25n

2

+25n

⇒83100×3=6000n+25n

2

+25n

⇒25n

2

+6025n−249300=0

Dividing by (25),

n

2

+241n−9972=0

⇒(n−36)(n+272)=0

⇒n=36,orn=−272

But

′

n

′

can not be negative.

∴

n=36