1956 AMC 12 Problem 47
Attempt Problem 47 of the 1956 AMC 12 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1956 AMC 12 solutions, or check the answer key.
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47.
An engineer said he could finish a highway section in days with his present supply of a certain type of machine. However, with more of these machines the job could be done in days. If the machines all work at the same rate, how many days would it take to do the job with one machine?
Answer: D
Small hint:
Let be the present number of machines and measure work in machine-days
Big hint:
Equate with
Solution:
If there are presently machines, the job requires machine-days. With three more machines it requires machine-days, so giving The job therefore requires machine-days, so one machine would take days.
Thus, the correct answer is D.