Question

Question of 2nd class

A man borrow 8000 and agrees to repay with a total interest of 1360 in 12
monthly instalments. Each instalment being less than the preceding one by ₹40. Find the amount of the first and last instalment.​

Answer 1

Answer:

The amount of money that man borrows is Rs8000 and the interest he has to pay is Rs1360.

The total money he has to pay is,

8000+1360=Rs9360

Since, he has to pay in 12 installments with a difference of 40 in each installment, then, it will form an A.P. where d=−40, n=12 and S

n

=9360.

Therefore,

sn=9360

9360=6(2a−440)

1560=2a−440

2a=2000

a=1000

The last term in A.P. is,

=a+(n−1)d

=1000+(12−1)(−40)

=1000−440

=560

Therefore, the first installment is Rs1000 and the last installment is Rs560.