ManishKM1 wrote:

5 drill machines can drill 15 meters in 5 hours. Assuming the speed of each machine to be the same, how many machines would be needed to drill 60 meters in 2 hours?

A)8

B)16

C)23

D)50

E)60

Find a machine's individual rate from the first information, and use it to solve the question.

W = (# of machines) * (indiv.) rate * time

W = 15, # of machines = 5, rate = ??, time = 5

15 = 5 * rate * 5

15 = 25 * rate

Individual rate = \(\frac{15}{25}=\frac{3}{5}\) in meters/hour

At that rate, how many machines are needed to drill 60 meters in 2 hours?

W = (# of machines) * (indiv.) rate * time

W = 60, # of machines = ??, rate = \(\frac{3}{5}\), time = 2

60 = (# of machines) * \(\frac{3}{5}\) * 2

60 = (# of machines) * \(\frac{6}{5}\)

# of machines = \(\frac{60}{(\frac{6}{5})}= 60 * \frac{5}{6}=\)

50 Answer D

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