Question

(b) Ms Sarkar opened a cumulative deposit account of monthly instalment of 200 at 9% pa
simple interest. She earned a total interest of 1,767. How many instalments did she pay?​

Answer 1

Given:

(i) Ms Sarkar opened a cumulative deposit account of monthly instalment of 200 at 9% pa  simple interest.

(ii) She earned a total interest of 1,767.

To find:

(i) Number of installments.

Solution:

Given, the cumulative deposit per month (P) is Rs 200

Time period = t months.

Rate (R)  = 9% p.a.

Interest money = Rs 1767

Total principal in 1 month = P*t*(t+1)/2

= 200t(t+1)/2

= 100t(t+1)

= 100t² + 100t

As, Interest = (Principal for 1 month*R)/(12*100)

⇒ 100t² + 100t = 1200*1767/9

⇒ t² + t = 2356

⇒ t² + t - 2356 = 0

On solving it, we get t approximately equal to 48 months

So, Ms Sarkar paid 48 installments.

Answer 2

Step-by-step explanation:

Ms Sarkar opened a cumulative deposit account of monthly instalment of 200 at 9% pa

simple interest. She earned a total interest of 1,767. How many instalments did she pay?