JAMB Mathematics 2019 Objective — Question 39
Question 39 of 40 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2019 Objective paper, with the correct answer and a full explanation.
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A train moves from P to Q at an average speed of 90km/h and immediately returns from Q to P through the same route at an average speed of 45km/h. Find the average speed for the entire journey
- A. 55km/h
- B. 60km/hCorrect
- C. 67.5km/h
- D. 75km/h
Explanation
Average speed for a round trip = 2×v₁×v₂/(v₁+v₂) = 2×90×45/(90+45) = 8100/135 = 60km/h.
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