Question

a man repays a debt of Rs 4860 by paying Rs 30 in the first month and then increase the amount by Rs15 every month .How long will it take him to clear the debt​

Answer 1

Answer:

Step-by-step explanation:

Here, a = 20,

d = 15 (As payment increases by Rs. 15)

and S(n) = 3

We know that,

S(n) = n/2[2a + (n - 1)d]

Putting all the values, we get

⇒ 3250 = n/2[2 × 20 + (n - 1) (15)]

⇒ 3250 × 2 = n[40 + 15n - 15]

⇒ 6500 = n[25 + 15n]

⇒ 1300 = n[5 + 3n]

⇒ 3n² + 5n - 1300 = 0

⇒ 3n² + 65n - 60n - 1300 = 0

⇒ n(3n + 65) - 20(3n + 65) = 0

⇒ (n - 20) (3n + 65) = 0

⇒ n = 20, - 65/3 (As n can't be negative)

⇒ n = 20

Hence, men will take 20 months to clear the loans.