Multiple choice

Carpenter $A$ can make a chair in $6$ hours, carpenter $B$ in $7$ hours and carpenter $C$ in $8$ hours. If each carpenter works for $8$ hours per day, how many chairs will be made in $21$ day?

  1. $61$
  2. $67$
  3. $73$
  4. $79$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carpenter A makes 8/6 chairs/day, B makes 8/7, C makes 8/8. Total per day = 8/6 + 8/7 + 1 = (28+24+21)/21 = 73/21. In 21 days, total = (73/21) * 21 = 73.

AI explanation

Working 8 hours a day for 21 days gives each carpenter 168 total hours. Dividing this by their individual chair-making times gives their production as 168 divided by 6 equals 28 chairs for A, 168 divided by 7 equals 24 chairs for B, and 168 divided by 8 equals 21 chairs for C. Adding these together gives a total of 28 plus 24 plus 21, which equals 73 chairs. They will make 73 chairs.

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