Multiple choice

A can do a job 12 days, B is 60% more efficient than A. How many days B will take to complete the job alone?

  1. 8 days

  2. 7.5 days

  3. 12 days

  4. 3 days

  5. 21 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If A takes 12 days, his rate is 1/12. B is 60% more efficient, so B's rate is 1.6 * (1/12) = 1.6/12 = 16/120 = 2/15. Time for B = 1 / (2/15) = 7.5 days.

AI explanation

If B is 60 percent more efficient than A, the ratio of their efficiencies is 1 to 1.6, which means the ratio of the time they take is 1.6 to 1. Since A takes 12 days, B takes 1.6 multiplied by 12 divided by 1 days. This results in B taking 7.5 days to complete the job alone.

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