How many fighters who were being tracked and who had 30 to less than 40 coins in 1980 remained active until 2010?
Refer to the bar graph provided with this set.
Refer to the bar graph provided with this set.
Answer and solution
Correct answer: D
Solution
Answer: D — 190
1. The starting bracket is 30–40 in 1980.
2. Thirty years add 30 coins, so find 60–70 in 2010.
3. Read the 2010 male and female bars: 90 and 100 respectively.
4. Combine the two genders: 90+100=190. Do not use the 2010 bracket 30–40 or the 2020 bars.
5. Answer: D, 190.
Detailed setup and verification:
This is one cohort and both genders. Starting 30–40 in 1980 becomes 60–70 in 2010 because 30 years have elapsed. Read only the 2010 male/female pair at that bracket: 90 and 100.
The result 190 is at most the cohort’s initial 500 fighters, as it should be. The other chart values 110 and 310 can arise from unrelated years or brackets; use the year, cohort and gender filters before doing any arithmetic.
Verification: 1. The starting bracket is 30–40 in 1980.
2. Thirty years add 30 coins, so find 60–70 in 2010.
3. Read the 2010 male and female bars: 90 and 100 respectively.
4. Combine the two genders: 90+100=190. Do not use the 2010 bracket 30–40 or the 2020 bars.
5. Answer: D, 190.
Trap to avoid: Use the exact requested cohort, statistic or rank condition; the worked check above establishes the result.
1. The starting bracket is 30–40 in 1980.
2. Thirty years add 30 coins, so find 60–70 in 2010.
3. Read the 2010 male and female bars: 90 and 100 respectively.
4. Combine the two genders: 90+100=190. Do not use the 2010 bracket 30–40 or the 2020 bars.
5. Answer: D, 190.
Detailed setup and verification:
This is one cohort and both genders. Starting 30–40 in 1980 becomes 60–70 in 2010 because 30 years have elapsed. Read only the 2010 male/female pair at that bracket: 90 and 100.
The result 190 is at most the cohort’s initial 500 fighters, as it should be. The other chart values 110 and 310 can arise from unrelated years or brackets; use the year, cohort and gender filters before doing any arithmetic.
G Strategy shortcut
Method: 1980 bracket 30–40 shifts to 2010 bracket 60–70: 90M+100F=190.Verification: 1. The starting bracket is 30–40 in 1980.
2. Thirty years add 30 coins, so find 60–70 in 2010.
3. Read the 2010 male and female bars: 90 and 100 respectively.
4. Combine the two genders: 90+100=190. Do not use the 2010 bracket 30–40 or the 2020 bars.
5. Answer: D, 190.
Trap to avoid: Use the exact requested cohort, statistic or rank condition; the worked check above establishes the result.
G Strategy: Method: 1980 bracket 30–40 shifts to 2010 bracket 60–70: 90M+100F=190. Verification: 1. The starting bracket is 30–40 in 1980. 2. Thirty years add 30 coins, so find 60–70 in 2010. 3. Read the 2010 male and female bars: 90 and 100 respectively. 4. Combine the two genders: 90+100=190. Do not use the 2010 bracket 30–40 or the 2020 bars. 5. Answer: D, 190. Trap to avoid: Use the exact requested cohort, statistic or rank condition; the worked check above establishes the result.