Question 718680
the time t required to do a certain job varies inversely as the number of people in working (assuming all work at the same rate)
 it takes 4 hours for 20 people working together to wash and wax all the floors in a building
Find the no. of man-hrs required to do the job
4 * 20 = 80 man-hrs
:
 how long would it take 25 people working together to complete the same job
let t = time required with 25 people
25t = 80
t = 80/25
t = 3.2 hrs
:'
you can also do this with a inverse ratio relationship
{{{t/4}}} = {{{20/25}}}
cross multiply
25t = 4 *20
t = 80/25
t = 3.2 hrs