Official Explanation
Note that the sectors in the manufacturing industry circle graph separate the unemployed manufacturing industry workers into five groups by length of unemployment; also, the percent of workers within each of the five groups is given. Also note that there are 10 million lengths of unemployment, one length for each of the 10 million workers. Since the lengths are rounded to whole numbers of weeks, most of the 10 million lengths must be repetitions. The median length of unemployment is the average of the two middle lengths when the lengths are listed in order from least to greatest; that is, the median is the number at which 50% of the lengths have been listed.
To find the median length, first note that the group with the shortest unemployment lengths, 1 to 4 weeks, accounts for the first 40% of the lengths in the ordered list. Then, because the group with the next longer lengths, 5 to 10 weeks, accounts for the next 20% of the lengths in the list, the number at which 50% of the lengths have been listed is in this group. So the median length is in the 5-to-10 week interval. Among the answer choices, the only choice that is in the 5-to-10 week interval is Choice B, 8.
The correct answer is Choice B.