Question

Dinesh opened a recurring deposit account with State Bank of India. He deposited Rs. 900 per month at `7.5%` per annum. He received Rs. 1687.5 as interest. Find the time period of his deposit. (in year)
A. 3
B. 3.5
C. 2.5
D. 2

Answer 1

Correct Answer - D
Let the time period T years.
T years = 12 T months. Interest received by him
`=(900)((12T)(12T+1))/(2)((1)/(12))((7.5)/(100))=1687.5`
`(9(T)(12T+1)(7.5))/(2)=16,687.5`
`T(12T+1)=((1687.5)(2))/((9)(7.5))=50" "(1)`
`12T^(2)+T-50=0`
`12T^(2)-24T+25T-50=0`
`12T(T-2)+25(T-2)=0`
`(12T+25)(T-2)=0`
`T=(-25)/(12)or 2
But `T gt0`
`thereforeT=2.`