A loan of Rs 4000 is cleared in monthly instalments that form an AP. The first instalment is Rs 100 and every later instalment is Rs 20 more than the one before. In how many months is the loan fully repaid?

Question

Accepted Answer

16. a = 100, d = 20 and S_n = 4000. So n/2[200 + 20(n-1)] = 4000 gives n(90 + 10n) = 4000, that is n^2 + 9n - 400 = 0. Then n = -9 ± √81 + 16002 = -9 ± 41/2, so n = 16 or n = -25. A negative number of months is impossible, so -25 is rejected and n = 16. (S_15 = 3600, still short of the loan.)

A loan of Rs 4000 is cleared in monthly instalments that form an AP.
The first instalment is Rs 100 and every later instalment is Rs 20 more than the one before.
In how many months is the loan fully repaid?

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More Class 10 Sum of n Terms of an AP practice

A loan of Rs 4000 is cleared in monthly instalments that form an AP.The first instalment is Rs 100 and every later instalment is Rs 20 more than the one before.In how many months is the loan fully repaid?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 Sum of n Terms of an AP practice

A loan of Rs 4000 is cleared in monthly instalments that form an AP.
The first instalment is Rs 100 and every later instalment is Rs 20 more than the one before.
In how many months is the loan fully repaid?