Question

If 10 men working 7 hours a day dig a trench 147metre long how many men working 8 hours a day will dig a trench 168 metre long

Answer 1

here approximately8men should work to complete their task

Answer 2

According to your question,
10 men working 7 h trench = 147 m

so, 1 man working 7 h trench = 147/10 m
      1 man working 1 h trench = 147/70 = 2.1 m

therefore, 1 man working 8 h trench = 2.1*8 m = 16.8 m
since,       16.8 m trench in 8 h by 1 man
                 168 m trench in 8 h by = 1 /16.8 * 168 = 10 men