Question

A man saved Rs 16500 in ten years. In each year after the first he saved Rs 100 more than he did in the preceding year. How much did he save in the first year?

Answer 1

Amount of saving in ten years = Rs 16500 

S₁₀ = 16500, d = 100 

S_n = (n/2) [2a + (n – 1)d] 

S₁₀ = (10/2) [2a + 9d] 

16500 = (10/2) [2a + 900] = 5(2a + 900) 

16500 = 10a + 4500 ⇒ 16500 – 4500 = 10a 

12000 = 10a 

a = 12000/10 = 1200 

Amount saved in the first year = Rs 1200