Problema Solution
If 4 boys can shovel a driveway in 2 hours, then how many minutes will it take 5 boys to do the job?
Answer provided by our tutors
the number of boys 'b' working is inversely proportional with the time 't' needed to finish the job:
b*t = k, where k is constant
knowing that b = 4 boys, t = 2 hr we find k:
k = 2*4
k = 8
now we know that b*t = 8
t = 8/b
if b = 5 boys we find for t:
t = 8/5
t = 1 3/5 hr
t = 1 hr 3*60/5 min
t = 1 hr 26 min
t = 96 min (since 1 hr = 60 min)
5 boys will need 96 min to do the job.