Question

One bricklayer can build a wall in 6 hours. Another bricklayer could build the same wall in 4 hours. If they work together, how long will it take to build the wall?

Answer 1

they work together, it will take 2.4 hours to build the wall.

Explanation:

One bricklayer can build a wall in 6 hours.

One hour work =
`(1)/(6)`

Another bricklayer can build the same wall in 4 hours.

One hour work =
`(1)/(4)`

They can together, how long will take them to build the wall.

Let's take "t" the time taken to build the wall.

The sum of their work rate = 1 (To build the wall)

`(t)/(6) + (t)/(4) = 1`

Now we have to solve this equation. Take LCD of 6 and 4.

The LCD (least common divisor) of 6 and 4 is 12.

`(2t + 3t)/(12) = 1`

5t = 12*1

5t = 12

Dividing both sides by 5, we get

t =
`(12)/(5)`

t = 2.4 hours.

So, they work together, it will take 2.4 hours to build the wall.