Multiple choice

Rahul and Priya can complete a certain task in 20 days when working together for 8 hours a day. If Rahul works alone at his usual efficiency for 6 hours every day, and Priya works alone for 8 hours every day with 25% more efficiency than usual, they can finish the task in 25 days. In how many approximate days will Rahul alone complete the task at his usual efficiency if he works for 8 hours every day?

  1. 20 days

  2. 22 days

  3. 24 days

  4. 26 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let R and P be their hourly work rates. (R+P)*8*20 = 1 (total work). Also, (R*6 + P*1.25*8)*25 = 1. Solving these equations: 160R + 160P = 1 and 150R + 250P = 1. Solving for R gives R = 1/176. Rahul completes the task in 176/8 = 22 days.

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