8 persons can build a wall 140m long in 42 days. In how many days can 30 persons complete a similar wall 100 m long?	Select:  A) 12  B) 10  C) 8  D) 6  E) 5
Explanation :   More persons, less days(indirect proportion)   More length of the wall, more days(direct proportion)   ⇒ 8 × 100 × 42 = 30 × 140 × x   ⇒ x = (8 × 100 × 42)/(30 × 140) = (8 × 100 × 14)/(10 × 140) = (8 × 100)/(10 × 10) = 8. Answer : Option 8
<result>C</result>
8 persons can build a wall 140m long in 42 days. In how many days can 30 persons complete a similar wall 100 m long?