Question

If 15 workers can build a wall in 48 hours, how many workers will be required to do the same work in 30 hours?
[2 marks]

Answer 1

Let the number of workers employed to build the wall in 30 hours be y.

Obviously the more number of workers, the faster they will build the wall.
So, the number of hours and number of workers vary in inverse proportion.
So,
$48\times 15=30\times y$
[1 mark]
$\therefore y=\frac{48\times 15}{30}=24$
To finish the work in 30 hours, 24 workers are required.
[1 mark]