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InterviewSolution
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2) A man borrows RS.800installment being less than the preceding one by Rs. 40. Find the amount of first and lastO and agrees to repay with a interest of RS. 1360 in 12 monthlyinstallment |
| Answer» <p>Money he borrows = 8000</p><p>Interest he will pay = 1360</p><p>Total money he will pay after = 8000 + 1360 = 9360</p><p>Now he will pay in 12 installments with a difference of 40 in each installment.</p><p>This is a form of AP,</p><p>where common difference d = -40, number of terms n = 12, and sum of 12 terms is 9360</p><p>So,</p><p>Sum of n terms in AP is</p><p>Sum = n/2 [ 2a + (n - 1)d ]</p><p>9360 = 12/2 [ 2a - 40(12 - 1) ]</p><p>9360 = 6 [ 2a - 440 ]</p><p>1560 = 2a - 440</p><p>2a = 2000</p><p>a = 1000</p><p>nth term in AP is given by:</p><p>a(n) = a + (n - 1)d</p><p>Last term = 1000 - 40(12 - 1)</p><p>=1000 - 440 = 560</p><p>Therefore first installment is 1000 and last one is 560</p> | |