Bob and Ted are in the plumbing business. Bob can do the plumbing hook-up for a new house in 4 hours; Ted does the same job in 6 hours. If they work together, how long will they take to hook up the plumbing in one house?
(2.1hr,2.4hr,5hr)
please help me

Question

Bob and Ted are in the plumbing business. Bob can do the plumbing hook-up for a new house in 4 hours; Ted does the same job in 6 hours. If they work together, how long will they take to hook up the plumbing in one house? 
(2.1hr,2.4hr,5hr)
please help me

yanasidlinskiy · Answer

You need to find the average. To do this, you add up all the numbers then divide them by how ever many numbers there are. 4+6=10; that's two numbers that you're adding so, 10/2 = 5 
5 hours.