Answer: A - This problem is asking you to find ½ of 1 percent change of 2,460. To do this mentally, first determine what 1 percent of the original number is, then half that. In this case, 1% of 2,460 is 24.6, and half of that is 12.3. Since you can’t have 3/10 of a person, we can approximate the population increase as 12 people. Add that to the initial 2,460 to find that the new population is 2,472.
Key takeaway: There are many types of percent problems you may encounter. It will be helpful to you if you know that you find 10% of a number by moving the decimal one place to the left and 1% of a number by moving the decimal point two places to the left.