Multiple choice

A can do a work in 20 days. B can do the same work in 25 days. In how many days the can do twice of the same work when they are working together?

  1. $\(\frac{100}{9}\) days$
  2. $\(\frac{50}{9}\) days$
  3. $90 days$
  4. $\(\frac{200}{9}\) days$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A's efficiency is 1/20 work per day, B's is 1/25 work per day. Combined efficiency is 1/20+1/25=9/100 work per day. For twice the work (2 units), time required is 2÷(9/100)=200/9 days. This is approximately 22.2 days.

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