Question

A principal of RS.500 per month for a period of 4 years . If at time of maturity she gets 28410 ,find the rate of interest.

Answer 1

Answer:

Rate of Simple interest  = 0.75 % per month or 9 % per annum.

Step-by-step explanation:

• He deposits Rs 500 per month for a period of 4 years.

• 4 years  = 48 months

• Amount deposited = 48 × 500  =  24000 rupees

• Amount received = 28410 rupees

• Interest received = 28410 - 24000  = 4410 rupees

Let,

Rate of interest = r%  per month  = 12r% per annum

• First month Deposit earn interest for 48 months.

• Second month for 47 months.

• and so on...

Simple interest = (P×R×T)/100

4410 =  (500r/100)(48 + 47 + 46 + ....................+  1 )

⇒ 4410 = (5r × 48 × 49)/2

⇒ 4410 = 120 × 49 × r

⇒ r = 4410/(120×49)

⇒ r = 4410/5880

⇒ r = 0.75% per month.

⇒ r = 0.75 ×  12

⇒ r = 9% per annum

∴ Rate of Simple interest  = 0.75 % per month or 9 % per annum

Answer 2

Answer:

principle-500

n-4 years =48 months

MV = 28410

let rate be r

MV=p*n+p*n(n+1)r/2*12*100

28410=500*48+500*48*49*r/2*12*100

28410-24000=490r

490r=4410

r=4410/490

=9%

rate of interest=9%.