A sum of ₹2,400 is invested for 4 years at R% p.a, simple interest and the simple interest received is ₹1,152. Find the amount received after 3 years when the same sum is invested at (R + 8) % p.a, simple interest.

₹3,840

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

1152 = \(\frac{2400 ×R× 4 }{100}\)

R = 12

New rate = ( R + 8 )% = ( 12 + 8 ) % = 20%

Simple Interest = \(\frac{2400 ×20 × 3 }{100}\)

= 1440

Amount = Principal + Simple Interest

= 2400 + 1440

= Rs. 3840