Question

A man borrows rs 8000 and agrees to repay with a total interest of rs 1360 in the monthly instalment.each instalment being less than the preciding one by rs 40.find the amount of the first and last instalment?

Answer 1

first installment-840&last installment- 280

Answer 2

Answer:

The amount of the first and last installment is Rs.500 and Rs.940 respectively .

Step-by-step explanation:

Principal = Rs.8000

Interest = Rs.1360

Amount = 8000+1360 = 9360

n = 12 months

Each installment being less than the preceding one by rs 40.

d = 40

Formula of sum of first n terms = $S_n=\frac{n}{2}(2a+(n-1)d)$

$S_{12}=\frac{12}{2}(2a+(12-1)40)$

$9360=\frac{12}{2}(2a+(12-1)40)$

$x=560$

First installment = Rs.500

Formula of nth term = $a_n=a+(n-1)d$

Last term =  $a_{12}=500+(12-1)(40)$

Last term =  940

Hence  the amount of the first and last installment is Rs.500 and Rs.940 respectively .