Multiple choice

A group of researchers started a data analysis project. On the first day, one researcher began the work. Each subsequent day, one additional researcher joined the project. This pattern continued until the project was completed in 20 days. If the efficiency of each researcher is the same, how many days would it take for a team of 14 researchers, working regularly, to complete the same project?

  1. 9

  2. 15

  3. 18

  4. 24
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The total work is the sum of researchers working each day: 1+2+3+...+20 = (20 * 21) / 2 = 210 man-days. If 14 researchers work every day, the time taken is 210 / 14 = 15 days.

AI explanation

The total amount of work is the sum of researchers working each day, calculated as the sum of the first 20 integers: (20 multiplied by 21) divided by 2, which equals 210 researcher-days. A regular team of 14 researchers working together has a daily capacity of 14 researcher-days. Dividing the total work of 210 researcher-days by the team's daily capacity of 14 gives 15 days.

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