If the annual increase in the population be 20% and the present population be 10,000. What will be the population after 3 years hence?

Step 1: Understand the problem The problem is asking for the population after 3 years if the current population is 10,000 and it increases by 20% annually.

Step 2: Identify the formula to use The formula to use in this case is the compound interest formula, which is A = P(1 + r/n)^(nt). However, since the population increases annually, n will be 1. So, the formula simplifies to A = P(1 + r)^t.

Step 3: Substitute the values into the formula In this case, P = 10,000 (the present population), r = 20/100 = 0.2 (the annual increase rate), and t = 3 (the number of years). Substituting these values into the formula gives A = 10,000(1 + 0.2)^3.

Step 4: Solve the equation First, calculate the value of (1 + 0.2)^3 = 1.2^3 = 1.728. Then multiply this by 10,000 to get A = 10,000 * 1.728 = 17,280.

So, the population after 3 years will be 17,280.