A man Can do a job in 6 days and his son can do it in 18 days

A man Can do a job in 6 days and his son can do it in 18 days. How many days would in take them to do the job if they worked together ? plz answer me option 1) 4.5 days 2) 5 days 3) 4days 4) 4.5days

1/6 + 1/18 = 1/x where x is the time it takes the man and his son to complete the job together.

x = 1/(1/6 + 1/18) = 18/(4) = 9/2 or 4.5 days

Hi Saggie sk, as man does in 6 days, the part done by him in one day is 1/6. For son he does 1/18 part in one day. So if they work together the part finished will be 1/6 + 1/18 ie 4/18 or 2/9.
So both together would take 9/2 ie 4.5 days. So option 1 is the right one.

4.5 Days.

In one day, the man would complete 1/6 of the job. The son would complete 1/18 of the job. So together they would complete 1/6+1/18 = 4/18 = 2/9 of the job. 1 job / (2/9) = 4.5

1m=6D
1/6m=D

1S=18D
1/18S=D

1/6 per day for man = 3/18 per day
1/18 per day for son = 1/18 per day

every day they get 4/18's done

4 days later would be 16/18's
5 days would be 20/18's

Answer = 4.5 days.

father: 6 days => 1 work
1 day => 1/6 work
x days => x/6 work
similarly, son x days => x/18 work
now,
x/6 +x/18 = 1
=> 4x = 18
=> x = 18/4 = 4.5

it is 4.5 days... it can be solved by simple work power concept

(18*6)/(18+6)=4.5 days

4.5 days

Thats one hard working kid. Good luck getting my kids to work like that.