How many of the male fighters who were being tracked and who had 20 to less than 30 coins in 1980 retired in the period 2000 to 2010?
Refer to the bar graph provided with this set.
Refer to the bar graph provided with this set.
Answer and solution
Correct answer: 40
Solution
Answer: 40
1. The original 20–30 male cohort becomes 40–50 in 2000 and 50–60 in 2010.
2. Read the 2000 male green bar at 40–50: 205.
3. Read the 2010 male purple bar at 50–60: 165.
4. The decrease in active tracked members is 205−165=40; no new fighters enter the tracked cohort.
5. Answer: 40.
Detailed setup and verification:
Use the male series and keep the initial cohort fixed. The 2000 count 205 is not compared with the 2010 bar at 40–50; the fighters themselves have moved up one bracket, so the correct 2010 count is 165 at 50–60.
The difference 205−165=40 is the number who retired during the interval. The starting 1980 count 250 would be needed for cumulative retirements since 1980, but the question starts its interval at 2000, so subtracting from 250 would answer a different question.
Verification: 1. The original 20–30 male cohort becomes 40–50 in 2000 and 50–60 in 2010.
2. Read the 2000 male green bar at 40–50: 205.
3. Read the 2010 male purple bar at 50–60: 165.
4. The decrease in active tracked members is 205−165=40; no new fighters enter the tracked cohort.
5. Answer: 40.
Trap to avoid: Use the exact requested cohort, statistic or rank condition; the worked check above establishes the result.
1. The original 20–30 male cohort becomes 40–50 in 2000 and 50–60 in 2010.
2. Read the 2000 male green bar at 40–50: 205.
3. Read the 2010 male purple bar at 50–60: 165.
4. The decrease in active tracked members is 205−165=40; no new fighters enter the tracked cohort.
5. Answer: 40.
Detailed setup and verification:
Use the male series and keep the initial cohort fixed. The 2000 count 205 is not compared with the 2010 bar at 40–50; the fighters themselves have moved up one bracket, so the correct 2010 count is 165 at 50–60.
The difference 205−165=40 is the number who retired during the interval. The starting 1980 count 250 would be needed for cumulative retirements since 1980, but the question starts its interval at 2000, so subtracting from 250 would answer a different question.
G Strategy shortcut
Method: Same cohort: 2000 male 40–50=205;2010 male 50–60=165. Difference 40.Verification: 1. The original 20–30 male cohort becomes 40–50 in 2000 and 50–60 in 2010.
2. Read the 2000 male green bar at 40–50: 205.
3. Read the 2010 male purple bar at 50–60: 165.
4. The decrease in active tracked members is 205−165=40; no new fighters enter the tracked cohort.
5. Answer: 40.
Trap to avoid: Use the exact requested cohort, statistic or rank condition; the worked check above establishes the result.
G Strategy: Method: Same cohort: 2000 male 40–50=205;2010 male 50–60=165. Difference 40. Verification: 1. The original 20–30 male cohort becomes 40–50 in 2000 and 50–60 in 2010. 2. Read the 2000 male green bar at 40–50: 205. 3. Read the 2010 male purple bar at 50–60: 165. 4. The decrease in active tracked members is 205−165=40; no new fighters enter the tracked cohort. 5. Answer: 40. Trap to avoid: Use the exact requested cohort, statistic or rank condition; the worked check above establishes the result.