Multiple choice

Directions: Study the following information carefully and answer the question that follows. Sonu can do a work in 15 days and Monu can do it in 18 days. However, together with Saif, they can do the work in 6 days. How long will Saif take to finish the work alone?

  1. 17 days

  2. 17.5 days

  3. 22.5 days

  4. 19.5 days

  5. 20 days
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sonu's rate = 1/15, Monu's rate = 1/18. Let Saif's rate be 1/x. Together they do 1/6 of the work per day. 1/15 + 1/18 + 1/x = 1/6. (6+5)/90 + 1/x = 1/6. 11/90 + 1/x = 15/90. 1/x = 4/90 = 2/45. x = 22.5 days.

AI explanation

Using the LCM method, let the total work be 90 units. Sonu's rate is 6 units per day (90 / 15) and Monu's rate is 5 units per day (90 / 18), giving a combined rate of 11 units per day. Since all three complete the work in 6 days, their combined rate is 15 units per day (90 / 6). Saif's rate is 4 units per day (15 - 11), so he alone requires 22.5 days (90 / 4). The result is 22.5 days.

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