Raju has a recurring deposit account in a bank of monthly investment ₹600 per month If the bank pays - Maths -

Question

Raju has a recurring deposit account in a bank of monthly
investment ₹600 per month If the bank pays an interest at 7%
p a and he receives ₹15450 on maturity, find the total time
for which the amount was held

Manbar Singh · Accepted Answer

Let the account be held for n months
Now, sum deposited per month, P = Rs 600Rate, r = 7%Interest = P × nn+12×12×r100=600×nn+12×12×7100=Rs7nn+14Now, maturity value = sum deposited + interest⇒15450 = 600n + 7nn+14⇒15450 = 2400n+7n2+7n4⇒61800 = 7n2 + 2407n⇒7n2 + 2407n - 61800 = 0⇒7n2 - 168n + 2575n - 61800 = 0⇒7nn-24 + 2575n-24 = 0⇒n-247n+2575 = 0⇒n-24 = 0   or   7n + 2575 = 0⇒n = 24     or   n = -25757RejectedThe time for which the account was held = 24 months = 2 years

Raju has a recurring deposit account in a bank of monthly investment ₹600 per month. If the bank pays an interest at 7% p.a. and he receives ₹15450 on maturity, find the total time for which the amount was held.