10 men, working 7 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 ? Choose one
A) 4 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 7 hours a dayays, More Hours {Indirect Proportion}   [men 15 10   days 12 18] ::7:x   =&gt;xâˆ—15âˆ—12=10âˆ—18âˆ—7   =&gt;x=10âˆ—18âˆ—7/ 15âˆ—12   =&gt;x=7   Option 7 hours a day
<result>D</result>
10 men, working 7 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 ?