Ram, who is half as efficient as Krish, will take 24 days to complete a task if he worked alone. If Ram and Krish worked together, how long will they take to complete the task?

Question

My answer was 16 days but the correct answers is 8 days, can somebody explain?

Chetanya Joshi · Accepted Answer

Since Ram is half as efficient as Krish, Krish will take half the time Ram takes to complete the task alone. Ram takes 24 days, so Krish will take 24 / 2 = 12 days.
Ram's work rate is 1/24 of the task per day.Krish's work rate is 1/12 of the task per day.
When working together, their combined work rate is:1/24 + 1/12 = 1/24 + 2/24 = 3/24 = 1/8
Thus, Ram and Krish together will take 8 days to complete the task.