Official explanation

The median age is the age of a person in the middle (half are younger, half are older) of the population stack. So, as a first step, figure out approximately how many members of the female population there are. Remember that the female graph is on the right.

Since each of the 13 female age cohorts from under 5 through 60 to 64 has about 100 hundred thousand people, you can estimate the total number of women under 65 (in hundreds of thousands):

Approximate number of women under 64 = 13 × 100 = 1,300

The next step is to read the approximate number of women in the older cohorts from the chart and jot them down:

65 to 69: » 65

70 to 74: » 50

75 to 79: » 42

80 to 85: » 35

85+ : » 38

Then use the calculator to add up the number of women 65 and older:

Number of women at least 65 years old = 65 + 50 + 42 + 35 + 38 = 230

So there are approximately 1300 + 230 = 1,530 hundred thousand women.

The median woman is the 1,530 ÷ 2 = 765 hundred thousandth woman. That woman would be in the 8th age cohort, counting up from under 5’s, since each of those cohorts has about 100 hundred thousand women. So, the median woman would be in the 35-to-39-year-old cohort.

Even if your estimate were off slightly (for example, if you found that the median woman’s age was 40 to 44), answer C, which is 46, would still be too high.

The correct answer is B.