10 men, working 3 hours a day can complete a work in 18 days. How many hours a day must 15 men work to complete the work in 12 days ? Pick one:
A) 3 hours a day
B) 5 hours a day
C) 6 hours a day
D) 7 hours a day
E) 8 hours a day
Explanation:   More Men, Less Hours {Indirect Proportion}   Less Days, More Hours {Indirect Proportion}   [men 15 10   days 12 18] ::3:x   =&gt;xâˆ—15âˆ—12=10âˆ—18âˆ—3   =&gt;x=10âˆ—18âˆ—3/ 15âˆ—12   =&gt;x=3   Option 3 hours a day
<result>A</result>
10 men, working 3 hours a day can complete a work in 18 days. How many hours a day must 15 men work to complete the work in 12 days ?