If 5 workers build a wall in 12 days, how long would 6 workers take, working at the same rate?

  • A. 10 days
  • B. 14 days
  • C. 12 days
  • D. 15 days

Explanation

The total work is 5 multiplied by 12, that is 60 worker days, and dividing by 6 workers gives 10 days. More workers means fewer days, an inverse proportion, so an answer larger than 12 must be wrong at a glance. Checking the direction of the relationship first prevents most errors here.

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