Present age of P is 15 years, and he invested Rs.4500 at 20% annual Compound Interest while Q invested Rs.5824 at 25% annual Compound Interest. When they both turn 18 years, interest amount received by both of them is same, then how old are Q at present?
The correct option is (B): 16 years. Let at present Q is 'x' years younger to become 18 years old. Interest amount received by P when he turns 18 years = 4500 * [(1.2)3-1] = Rs.3276 Interest amount received by Q when he turns 18 years = 5824 * [(1.25) x-1] = 3276 1.25x - 1 = \(\frac{9}{16}\) 1.25x = (\(\frac{9}{16}\)) + 1 1.25x = 1.5625 = 1.252 x = 2 Present age of Q=18-2=16 years.