f a sum of money at simple interest triples in 18 years, it will become 5 times in:Options22 years36 years 28 years20 years

The problem is about simple interest.

Step 1: Understand the problem The problem states that a sum of money triples in 18 years. This means that the interest earned in 18 years is twice the original sum of money (since the original sum of money plus twice that sum gives us the tripled amount).

Step 2: Formulate the problem mathematically If we let P be the original sum of money and r be the rate of interest, then we can write the simple interest formula as follows: I = Prt, where I is the interest, r is the rate of interest, and t is the time.

In this case, we know that 2P = Pr18, or r = 2/18 = 1/9 per year.

Step 3: Solve the problem We want to find out when the sum of money will become 5 times the original amount. This means that the interest earned will be 4 times the original sum of money (since the original sum of money plus four times that sum gives us five times the amount).

We can use the simple interest formula again to find this out: 4P = Prt, or t = 4/r = 4/(1/9) = 36 years.

So, the sum of money will become 5 times the original amount in 36 years. Therefore, the correct option is 36 years.