Question

A person pays 975 as monthly installment each installement being less than former by 5 the amount paid in first installment is 100 . In what time the amount will be paid

Answer 1

As given in problem, A=100, D=-5

Formula is:

Sum of AP = n/2 [2a+(n-1)d]

Therefore, 

975 = n/2 [200+(n-1)-5]

1950 = n(200-5n+5)

1950 = 205n-5n^2

5n^2-205n+1950 = 0

n^2-41n+391 = 0

n^2-26n-15n+390 = 0

n(n-26) - 15(n-26) = 0

Hence,

n = 15 or 26.

So,

n = 15 months.

Answer 2

Given; A person pays 975 as monthly instalments each instalment is less than the eye amount paid in the first instalment is 100

To Find; What is the amount that will be paid

Solution; It is given that A person pays 975 as monthly instalments each instalment is less than the former by 5 the amount paid in the first instalment is 100

First instalment a= 100

Decrement d=5

Total amount Sn= 975

solving this we get n as 15

Hence the amount will be paid in fifteen months