- A13.33 km/h
- B12.5 km/h
- C12 km/h
- D14 km/h
Step-by-Step Solution
Time = 2 + 1 = 3 h. Average = 40 ÷ 3 = 13.33 km/h. (12.5 is the simple mean of the two speeds — wrong for unequal times.)
Answer: A) 13.33 km/h
A boat goes 30 km downstream at 15 km/h and then 10 km upstream at 10 km/h. What is its average speed for the 40 km?
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