Multiple choice

Rambo finished 3/5th of a work in 9 days. Then, Shaun joined him and they together finished the remaining work in another 4 days. In how many days could Shaun alone finish the work?

  1. 30 days

  2. 35 days

  3. 22 days

  4. 28 days

  5. 32 days
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rambo finishes 3/5 of the work in 9 days, so he does 1/15 of the work per day. In the next 4 days, Rambo and Shaun finish the remaining 2/5 of the work. Thus, (Rambo + Shaun) rate = (2/5) / 4 = 1/10 per day. Shaun's rate = 1/10 - 1/15 = 3/30 - 2/30 = 1/30. Shaun takes 30 days to finish the work alone.

AI explanation

Using the unitary method, Rambo completes 3/5th of the work in 9 days, so his rate is 3/5 divided by 9, which equals 1/15 of the work per day. The remaining work is 1 minus 3/5, giving 2/5. Rambo and Shaun complete this remaining 2/5th of the work in 4 days, making their combined daily rate 2/5 divided by 4, which equals 1/10. Shaun's daily rate is their combined rate minus Rambo's rate, yielding 1/10 minus 1/15, which simplifies to 1/30. Therefore, Shaun alone could finish the entire work in 30 days.

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