Question

mr.gupta has a recurring deposit account of rs.500 per month at 6.5 Percent per annum if he gets rs.812.5 as interest at the time of maturity find the total time for which the account was held
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Answer 1

The total time for which the account was held is 24 months (2 years).

Given, deposit (P) = Rs 500/month

Rate (R) = 6.5% p.a

Interest (I) = Rs 812.5

Let time period be 'n' months.

We know,

I = [n(n+1)/2] × [(P×R)/(100×12)]

Putting the respective values, we get:

n(n+1) = 600

⇒n²+n-600 = 0

⇒ n²+ 25n - 24n -600 = 0

⇒ n(n+25) -24(n+25) = 0

⇒ (n+25)(n-24) = 0

By zero product rule, we get n = 24 months as time cannot be negative.

So, time taken is 24 months or 2 years.