Multiple choice

$A$ is twice as fast as workman as $B$ and together they finish a piece of work in 14 days. In how many days can $A$ alone finish the work?

  1. $18$ days
  2. $21$ days
  3. $24$ days
  4. $27$ days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let B's rate be x, then A's rate is 2x. Combined rate is 3x. 3x = 1/14, so x = 1/42. A's rate is 2x = 2/42 = 1/21. A takes 21 days.

AI explanation

Let the total work be the product of their combined speed and time, which is $(2 + 1) \times 14 = 42$ units. Since A works at a speed of 2 units per day, dividing the total work by A's speed gives $42 / 2 = 21$ days for A to finish the work alone.

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