Multiple choice

Pannalal does 1/3rd of a job in 20 days, Saiprasad completes the rest of the job in 10 days. In how many days can they together do the job?

  1. 12 days

  2. 6 days

  3. 3 days

  4. 24 days
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pannalal does 1/3 of the job in 20 days, so he does the whole job in 60 days. Saiprasad does the remaining 2/3 of the job in 10 days, so he does the whole job in 15 days. Their combined rate is 1/60 + 1/15 = 5/60 = 1/12, meaning they finish in 12 days.

AI explanation

Pannalal completes 1/3 of the job in 20 days, so using the unitary method he can complete the entire job in 60 days. Saiprasad completes the rest of the job, which is 2/3, in 10 days, meaning he can complete the full job in 15 days. Taking the least common multiple of 60 and 15 as 60 units of total work, Pannalal works at 1 unit per day and Saiprasad works at 4 units per day. Their combined efficiency is 5 units per day, meaning they together finish the job in 60 divided by 5 days, which equals 12 days.

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