Multiple choice

Jack alone can do a piece of work in 6 days and Jonny alone in 8 days. Jack and Jonny undertake to do it for Rs. 3200. With the help of Rehan, they completed the work in 3 days. How much is to be paid to Rehan?

  1. Rs. 385

  2. Rs. 400

  3. Rs. 550

  4. Rs. 785

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Jack's efficiency is 1/6, Jonny's is 1/8. Together they do (1/6 + 1/8) = 7/24 per day. In 3 days, they do 3 * (7/24) = 7/8 of the work. Rehan does 1/8 of the work. Payment is proportional to work: (1/8) * 3200 = 400.

AI explanation

Calculate the total work as 24 units using the least common multiple of 6, 8, and 3. Jack completes 4 units per day and Jonny completes 3 units per day, giving a combined total of 7 units. Since all three complete the 24 units in 3 days, their combined daily rate is 8 units, meaning Rehan contributes 1 unit per day. Rehan therefore completes 3 out of the 24 total units, so his proportional share of Rs. 3200 is Rs. 400.

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