# If eight men can dig a hole in 4 hours, how long will take the five men to dig the same hole?

Mar 30, 2015

6.4 hours;
You use the proportion (inversely proportionality)
if n° of men decreases $8 \to 5$
Time must increase $4 \to x$ so inverting:
$\frac{8}{5} = \frac{x}{4}$
$x = \frac{32}{5} = 6.4$

Mar 30, 2015

(Assuming the men don't get in each others' way)

if 8 men can dig a hole in 4 hours
the hole represents $8 \times 4 = 32$ man-hours of work.

5 men can complete 32 man-hours of work in
$\frac{32 \cancel{m a n} h o u r s}{5 \cancel{m e n}} = 6.4 h o u r s$