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A car travels the first half of a distance
between two places a speed of 30 km/hr
and the second half of the distance a 50
km/hr. The average speed of the car for
the whole joumey is
Answers
Answer:
If a car travels the first half of a distance with a speed of 30km/h and the remaining half distance with a speed of 50km/h. What is its average speed?
Two roads that cruise to the BMW 6 series Gran Turismo.
Several people already did the math, but when I see a question like this I like to consider why someone would ask such a question, beyond they want help with fairly simple math. There is likely a concept that causes confusion, and to really get to the crux of what the questioner might want to learn that should be addressed.
Many people would jump to the answer “40 kph” because if half is 30 and half is 50 that seems to be a reasonable average. And it is, if they each covered half the time of a total trip. If you traveled a half hour at 30 then a half hour at 50, it’s the same distance someone travelling at a steady 40 would cover. However, when we allow the slower speed enough time to cover half the distance, then we are traveling at the higher speed for less time. The real knowledge to be imparted might be that the average is a “clean” 40 when the times are split into equal parts, not when the distance is split evenly.
This also provides another way to calculate the answer. at 3/5 the speed the 30 kph half will take 5/3 as long as the 50 kph. Divide the time into 8 parts and 5/8 is spent at 30, 3/8 is spent at 50. The average speed will follow this 5 to 3 ratio. being 3/8 of the way between the two speeds.
There is a 20 kph difference between the speeds: The average is 3/8 of 20 above 30 = 3 7.5 Of course you could also say it is 5/8 of 20 less than 50 = 37.5.
Answer:
40km/hr
Explanation: