Question

Bina has a recurring deposit account of rupees 400 per month si 10% per month if she gets 30,100 rupees at the time of maturity find the total time for which the account was held. please don't give a spam answers its urgent please requested please give me the correct answer only if you know please​

Answer 1

If P is deposit amount every month and "r" is rate of interest, then interest of cumulative doppsit of "n" months is given by,

I = P * n(n+1) /2*12 * r/100

therefore, we have 400 * n(n+1) /2 * 12 * 10/100 = 30100 - 400n

Above equation is simplifyed asas : n²+ 241n - 18060=0

after factorising LHS of the equation , it is written as

(n+301) (n-60) = 0

Hence "n" = 60 months = 5 years.