Multiple choice

A is thrice as good a workman as B and takes 10 days less to do a piece of work than B takes. B can do the work in _______.

  1. $12$ days
  2. $15$ days
  3. $20$ days
  4. $30$ days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let B take x days, A takes x/3 days. x - x/3 = 10. 2x/3 = 10. x = 15 days.

AI explanation

Using the efficiency method, let the time taken by B be x days, meaning A takes x minus 10 days. Because A is thrice as efficient, 3 multiplied by x minus 10 equals x. Solving this equation yields x equals 15 days.

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