Question

Aman saved Rs.32 during the first year, Rs.36 in the second year and in this way he increases his savings by Rs.4 every year. Find in what time his saving will be Rs.200.

Answer 1

Aman will save Rs. 200 within 5 years.

Step-by-step explanation:

(i) Given: Aman saved Rs.32 during the first year, Rs.36 in the second year and in this way he increases his savings by Rs.4 every year.  

Find: Find in what time his saving will be Rs.200.

Solution:

  Sum = Rs. 200

  a = 32

  d = 4

  Sum of AP = n/2 (2a + (n-1)d)

  200 = n/2 (2(32) + (n-1)4)

  200 = n/2 (64 + 4n -4)

  400 = 60n + 4n²

Dividing by 4, we get:

 n² + 15n - 100 = 0

 n² + 20n -5n - 100 = 0

 n (n+20) -5(n+20) = 0

 (n-5)(n+20) = 0

n can be +5 or -20

N can't be negative, so n = +5

Aman will save Rs. 200 within 5 years.