Multiple choice

5 skilled workers can build a wall in 20 days, 8 semi-skilled workers can build a wall in 25 days, 10 unskilled workers can build a wall in 30 days. If a team has 2 skilled, 6 semi-skilled and 5 unskilled workers, how long will it take to build the wall?

  1. 20

  2. 18

  3. 16

  4. 15
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Calculate the daily work rate for each worker type: skilled = 1/(5*20) = 1/100, semi-skilled = 1/(8*25) = 1/200, unskilled = 1/(10*30) = 1/300. The combined daily rate for the team is (2/100) + (6/200) + (5/300) = (6+9+5)/300 = 20/300 = 1/15. Thus, the time required is 15 days.

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