Question

a person has to pay Rs.975 by monthly installments each less then the former by Rs.5. the first installment is RS.100. the time by which the entire amount will be paid is

Answer 1

Answer:

Hay Guys!!!

time will be 15 months

Step-by-step explanation:

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.

Hope it may help you ^_^