Question

Three workers can do a job in 28 hours. How many more workers are needed to do this job in 12 hours?

Answer 1

Answer:

It will take 7 workers to do the work in 12 hours.

Step-by-step explanation:

We can use proportion to solve this problem, but first, we need to find out if it is a direct or indirect proportion.

As the number of workers increase the number of hours need to do the work/ the time taken to do the work decreases and as the workers decreases, the time taken to do the work increases, so this is an indirect proportion.

Since its an indirect proportion, the arrangement will be different from that of direct proportion, the values will be arranged such that they will be inverse with each other.

Let x be the number of workers needed to do the job in 12 hours

3 workers    =     x

 12 hours     =  28 hours

Cross- multiply

12 x =  84

Divide both-side of the equation by 12

$\frac{12x}{12}$  =  $\frac{84}{12}$

x = 7

It will take 7 workers to do the work in 12 hours.

Answer 2

So, 3 workers are to 28 hours and x is to 12 hours. That can be written as 

 3     28
---     --
x       12
Multiply them to get 94 over 12. 84 divided by 12 is 7.