Question

For a given G.P., If a = 10, r = 0.1 and T_n = 0.01; then find n.

Answer 1

a = 10, r = 0.1, T = 0.01, n =?

T_n = a.r^n-1

∴ 0.01 = 10(0.1)^n-1

∴ 0.01 / 10 = (0.1)^n-1

∴ 0.00 1= (0.1)^n-1

∴ (0.1)³ = (0.1)^n-1

∴ 3 = n – 1

∴ n = 4