Multiple choice

A can have a piece of work done in 8 days, B can work three times faster than the A, C can work five times faster than A. How many days will they take to do the work together?

  1. 3 days

  2. 8/9 days

  3. 4 days

  4. can't say

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A takes 8 days, so A's rate = 1/8 work per day. B works 3 times faster, so B's rate = 3/8 work per day. C works 5 times faster, so C's rate = 5/8 work per day. Combined rate = (1+3+5)/8 = 9/8 work per day. Time together = 1 ÷ (9/8) = 8/9 days.

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