Problem-Solving and Data Analysis practice question

Answer: B. 48 mph

Average speed = total distance / total time. Distance = 60(2) + 40(3) = 120 + 120 = 240 miles; time = 5 hours; 240/5 = 48 mph. Choice C (50) is the trap: you can't just average the two speeds when the times differ.

Why the other answers are wrong

A. 46 mph

No standard slip produces 46 — average speed is total distance ÷ total time: (120 + 120) ÷ 5 = 48 mph. Make sure you compute each leg's distance before dividing.

C. 50 mph

You averaged the two speeds (60 + 40)/2, but that only works when the two legs take equal time; here the car spends 2 hours at one speed and 3 at the other.

D. 52 mph

You paired the speeds with the wrong times: 60 mph for 3 hours and 40 mph for 2 hours gives (180 + 80)/5 = 52. The car goes 60 for 2 hours and 40 for 3.

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