ICSE Class 10 Answered

Recurring deposit interest I is

where p is principle amount deposited every month, n is number of months , r is rate of interest.

if Rs.300 is principal amoumt deposited monthly for a period of n months ,

then interest I of recurring deposit with 7% interest  is

Above expression is simplified as

7 n² + 2407 n - 61800 = 0

By solving above quadratic equation , we get  n = 24

Hence period of recurring deposit is 24 months.