Question

Three carpenters are installing some doors for a building.Carpenter A installs a door every 40 min, Carpenter B installs adoor every 1 h 20 min and Carpenter C installs a door every 1 h40 min. If they start installing three doors at the same time at9:15, at what time will they install doors at the same again?

Answer 1

The three carpeters were installing doors.

A installs at 40 mins

B installs at 1 h 20 mins = 60 + 20 = 80 mins

C installs at 1 h 40 mins = 60 + 40 = 100 mins

Now to find how many minutes it will take them to install three doors completely, we have to find the LCM of 40, 80 and 100.

The LCM of 40, 80 and 100 = 400.

So, it will take them 400 minutes to install three doors and start again

400 mins to hours is

360 mins = 6 hours. That is

`(360)/(60)=6\text{ hrs }`

400 - 360 = 40 mins

So, 400 mins = 6 h 40 mins.

So, to get what time they will install doors again after 9:15, we add 6 h 40 mins to 9:15.

This becomes 15:55 GMT

So, the answer is 15:55 GMT