20 आदमी किसी काम को 18 दिनों में कर सकते है वे 3 दिनों साथ काम करते है फिर 5 आदमी और आ जाते है तो काम और कितने दिनों में समाप्त हो जायेगा ?

Options

A. 12 days
B. 14 days
C. 13 days
D. 15 days

Answer

a

Explanation

(a) 20 men `to` 18 days
`implies` work done by them in 3. days working
Together `=1xx3=3` work
`implies` remaining work `=18-3=15` work
`implies` 15 work is to be done by `(20+5)=25` men `therefore ` Efficiency of 20 men =1
Efficiency of 1 man `=(5)/(20)=(1)/(4)`
`implies` so , efficiency of `(20+5)`
`implies` 25 men `=(1)/(4)=(5)/(4)` working days Required time `=("Work")/(efficency )~~ (15)/(5//4)=12` days
therefore 12 more days will be taken tp finish the remaining be taken to finish the reamaing work अंत : कार्य समाप्त करने में 12 दिन और लगेंगे
Alternate
20 men can do 18 days so total work `=18xx20=360`
20 men 3 days work `=20xx3=60`
remaining work` = 360-60=300`
After joining 5 men total men =20 +5
so `(300)/(25)=12 days`