At simple interest a certain sum amounts to ₹12,000 in 5 years and to ₹18,000 in 8 years. What is the rate of simple interest per annum on offer?

100%

ATQ,

Simple interest of 3 years = 18000 - 12000 = 6000

Simple interest of 1 years = 2000

Principal sum = 12000 - 5 ×  2000 = 2000

Simple Interest = \(\frac{Principal ×Rate × Time }{100}\)

2000 = \(\frac{2000 × Rate × 1 }{100}\)

Rate = 100%