Question

A team of 15 workers can do a job in 7 hours. How long would this work take if the team has 35 people?

Answer 1

I like to do these problems by gradually changing my ratios using logical steps. So it is given that:

15 workers: 7 hours: 1 job

Which means if there were 15 times fewer workers, it would take 15 times longer, where 15*7 is 105 hours:

1 worker: 105 hours: 1 job

Now from this ratio, if there were 35 times as many workers, the job will be completed 35 times faster, so 105/35 = 3 hours:

35 workers: 3 hours: 1 job

Thus it will take the team only 3 hours!