- If 10 people can do a piece of work in 5 days, working 2 hours a day, how long will 2 people take to do the same work, working 5 hours a day?
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8
5
10
`2
Total work = 10 × 5 × 2 = 100 person-hours. For 2 people working 5 hours daily: 100 ÷ 2 ÷ 5 = 10 days. The work rate changed from 20 person-hours/day to 10 person-hours/day, so it takes exactly twice as long.
To solve this question, we can use the concept of "work done" and "work rate".
Let's assume that the amount of work to be done is represented by "W". We are given that 10 people can complete this work in 5 days, working 2 hours a day.
So, the work done by 10 people in 1 day is (W/5) and in 1 hour is (W/5)/2 = W/10.
Now, we need to find out how long 2 people will take to do the same work, working 5 hours a day.
The work done by 2 people in 1 day is (W/t), where "t" is the number of days.
Since the work done by 10 people in 1 hour is W/10, the work done by 2 people in 1 hour is (W/10) * (10/2) = W/5.
Therefore, the work done by 2 people in 1 day is (W/5) * 5 = W.
From the above calculation, we can conclude that 2 people will take 1 day to complete the work.
Hence, the correct answer is option C) 10.