1/x will be the largest as the value approaches 0.
Thirty men take 20 days to complete a job working for 9hrs a day, how many hr(s) a day should 40 men to work to complete the job?
A. 8 B. 7.5 C. 7 D. 9
Correct Answer: B
Explanation
More men means less time needed to complete the joB. So, to find the number of hours per day for 40 men to complete the job in 20 days, the equation becomes (30 * 9 * 20) / (40 * x * 20) = 1, where x is the number of hours per day for 40 men. Solving for x gives x = 7.5.
