Question

On Monday 4 bricklayers took 3 hours to lay a total of 4200 bricks.

Answer 1

Hello!

The answer is:

It will take 4.5 hours for two bricklayers to lay a total of 3150 bricks.

Why?

From the statement, we know that on Monday, bricklayers took 3 hours to lay a total of 4200 bricks.

So, we have that the rate of the four bricklayers is given by the following equation:

$Production=Rate*Time\\\\Rate=\frac{Production}{time}$

$Rate=\frac{4200bricks}{3hours}=\frac{1400bricks}{hour}$

Therefore, we have that the rate of the four bricklayers is 1400 bricks per hour, meaning that each bricklayer can lay 350 bricks per hour.

Now, to calculate how many hours it will take to the 2 bricklayers to lay a total of 3150, we need to divide the calculated rate (for bricklayers) by two, since there are only 2 bricklayers working on Tuesday.

So, calculating the time, we have:

$Production=\frac{Rate}{2}*Time$

$3150bricks=\frac{\frac{1400bricks}{hour}}{2}*Time$

$3150bricks*2*\frac{1hour}{1400bricks}=Time$

$6300bricks*\frac{1hour}{1400bricks}=Time$

$Time=4.5hours$

Hence, we have that it will take 4.5 hours for two bricklayers to lay a total of 3150 bricks.

Have a nice day!