Multiple choice

A and B can do a piece of work in 6 2/3 days and 5 days respectively. They work together for 2 days and then A leaves. In how many days after that B will complete the work alone.

  1. 2 days

  2. 1 ½ days

  3. 3 days

  4. 3 ½ days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A's rate is 3/20 work/day and B's rate is 1/5 work/day. Together, they do (3/20 + 4/20) = 7/20 work/day. In 2 days, they complete 14/20 = 7/10 of the work. The remaining 3/10 work is done by B at 1/5 per day, taking (3/10) / (1/5) = 1.5 days.

AI explanation

Convert A's time to an improper fraction to find A's rate is 3/20 of the work per day, while B's rate is 1/5 of the work per day. Their combined daily work rate is 3/20 plus 4/20, which equals 7/20. In 2 days working together, they complete 14/20 of the total work, leaving 6/20 or 3/10 of the work remaining. Dividing this remaining work by B's daily rate of 1/5 gives (3/10) divided by (1/5), which results in 1 1/2 days for B to finish the work alone.

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