At first, I tried to answer the problem by taking an average. I added 40, 60 and x together and divided the sum by three. this gave me 60 for x. I thought this was the answer because I saw the word "average" and relied on what previous formulas I'd learn to find the answer.
I didn't answer correctly because I didn't fully take into account both aspects of speed, distance and time. After looking at the diagram a little closer, I realized that I needed to calculate how long the car had traveled and for what length of time before finding the third speed.
The car traveled 20 km at a speed of 40 km/hr, and another 10 km at a speed of 20 km/hr. To go 20 km at 40 km/hr would mean you traveled for half an hour. To go 10 km at 20 km/hr would mean you would have traveled for another half an hour. The question asks what speed you must go to average 40 km/hr. The reason we all answered incorrectly at first was because we viewed speed as a number rather than a measure of distance and time. The formula you would use to figure out the time traveled by each car would be t = v/d.
This problem made me realize that when solving a problem that seems confusing on the surface, most simply require you to step back and look at all the information given before trying to solve.
I made the same mistake until you helped me out in class. You easily analyzed your work to find the mistake that you had made and explained it in a way that people who had made the same mistake could fix it without difficulty. Great Job!
ReplyDeleteI thought that was interesting that you thought to take the average of the numbers. I definitely would not have thought of that. We definitely didn't have the same reaction to the trip problem! You actually thought of a probable way to solve the problem, when I just got scared and froze up. But after really looking hard at the question that was being asked, we were both able to find the right answer. My question to you would be, do you think that this experience has helped you to prepare for future issues so you don't make the same mistake?
ReplyDeleteI liked how when you got the wrong answer you were able to look back and see what you did wrong. Some advice I have would be to state the problem in the beginning for people who are not in your class.
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