Answers

2015-01-19T16:45:59+05:30
Days           Men           Hours
10                  20               12
 30                  x                  8

Ratio of days = 10 : 30 = 1 : 3
Ratio of Hours = 12 : 8  = 3 : 2
Ratio of men = 20 : x

Compound ratio of 1 :3  and 3 : 2 is 

1 : 3 :: 3 : 2  = 1×3 : 3×2 = 3 : 6  = 1 : 2

Ratio of men is inversely proportional to Days and Hours

20 : x = 2 : 1

2x = 20

x = 10

10 men required 

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