A contractor undertakes to complete the construction of a tunnel 720 meters long in 240 days and employs 50 men for the purpose. After 120 days, he finds that only 240 meters of the tunnel is complete. How many more men should be employ in order to complete the work in time? Choices.
A) 75 men
B) 80 men
C) 70 men
D) 60 men
E) 50 men

Rationale: "in 120 days , only 240 m of the tunnel is constructed by 50 men . the remaining 120 days , 480 m of the tunnel can be constructed by 120 men . additional number of men required = 120 - 50 = 70 men . answer : c"
Answer: C