AbdurRakib wrote:

A technician makes a round-trip to and from a certain service center by the same route. If the technician completes the drive to the center and then completes 10 percent of the drive from the center, what percent of the round-trip has the technician completed?

A) 5%

B) 10%

C) 25%

D) 40%

E) 55%

We can let the distance to the center = d, so the roundtrip distance = 2d.

Since the technician has driven to the center and completed 10 percent of the drive home, he has gone d + 0.1d = 1.1d. Thus, the percentage completed is:

(1.1d)/(2d) x 100

11/20 x 100 = 11 x 5 = 55 percent.

Alternate solution:

After the technician has driven to the center, he or she has completed half, or 50%, of the round trip. We know that the technician will drive a bit more, and without doing the math, we see that the only logical answer choice is 55%.

Answer: E

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