Study the following information carefully and answer the given questions. Data below represent number of people required for various project to be completed in various days :

If 0.5 Y people work on project B for 10 days and then 0.5Y people join the project after 10 days. How many days will it take to complete the Project B?

Options

A. 35 days
B. 40 days
C. 45 days
D. 50 days

Answer

B

Explanation

Work unit of project B in both situation 1 and situation 2 are same.
`rArr Y ( Y - 1) = (Y + 6) (Y - 6)`
`rArr Y^(2) - Y = y^(2) - 36`
`rArr Y = 36`
So, total work units ` = 36 xx 35 = 1260` According to the question :
`0 . 5 Y xx 10 + (0.5Y + 0.5Y) xx D = 1260`
`rArr 5 Y + YD = 1260`
`rArr YD = 12 60 - 180`
`rArr D = 1080 // 36`
`rArr D = 30`
Total days in which work completed = 30 + 10 = 40 days