Math, asked by fizafahim710p3s2uy, 1 year ago

A man borrows Rs 2500 and agrees to repay with a total interest of rs 380 in 12 monthly instalment each installment being less than the preceding one by rs 20 find amount of the first and last installment

Answers

Answered by sam2001envy
17
Given, amount to be repaid = Rs 2500 + Rs 380 = Rs 2880
No. of installments = No. of terms in the A.P. (n) = 12
Let the first installment be of value Rs.x
So, value of the succeeding installment = Rs. (x-20)
A.P.: x, x-20, x-40, ...         a = x, d = -20
Sum of the installments = 2880
i.e, 12/2{2x + (11 x -20)} = 2880
⇒ 6{2x - 220} = 2880
⇒2x - 220 = 480
⇒2x = 700  ⇒ x = 350
∴ Amount of first installment = Rs. 350
Amount of last installment = a12 = a + 11d = 350 -220 = Rs. 130
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