Question

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

Answer 1

S₁₀ = ₹ 16500

a, a + d, a + 2d ...

d = 100

n = 10

S_n = `"n"/2` (2a + (n – 1)d)

S₁₀ = 16500

S₁₀ = `10/2` (2 × a + 9 × 100)

16500 = 5(2a + 900)

16500 = 10a + 4500

10a = 16500 – 4500

10a = 12000

a = `12000/10` = ₹ 1200

∴ He saved ₹ 1200 in the first year