Bunuel wrote:

Working together at their respective constant rates, robot A and robot B polish 88 pounds of gemstones in 6 minutes. If robot A’s rate of polishing is 3/5 that of robot B, how many minutes would it take robot A alone to polish 165 pounds of gemstones?

(A) 15.75

(B) 18

(C) 18.75

(D) 27.5

(E) 30

Since Robot A works at \(\frac{3}{5}(60\)%) the rate at which Robot B works, together they do work of \(1.6(1+.6)\) robots.

1.6 robots polish 88 pounds in 6 minutes. In 6 minutes, Robot A(0.6 robot) polishes \(\frac{88}{1.6}*0.6\) or 33 pounds of gemstones.

Therefore, it will take Robot A (\(\frac{165}{33} = 5\)) 6 minute intervals =

30(Option E) minutes to polish 165 pounds of gemstones.

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