MathRevolution
==> In the original condition, he travels the total 150 miles by dividing it to two trips of 50 miles each. Hence, since there are 6 variables, E is most likely to be the answer. In order for C to be the answer, there must be a word “constant rate” mentioned.
Therefore, E is the answer.
Answer: E
1) John traveled the first 100 miles at the rate of 50 miles per hour
2) John traveled the last 100 miles at the rate of 50 miles per hour
Dear
MathRevolution,
I do not understand why the correct answer it E.
Booth statements gives us the actual rate and not any average. So we know for sure that in the first 100 miles his speed was always 50 mph. The same goes for the last 100 miles. Therefore we know for sure that he was driving at 50 mph the whole 150 miles trip. Or where did I go wrong?
Since the second 50 miles are overlapped for both conditions. The following is the explanation.
Let a, b and c be numbers of hours for the first 50 miles, the second 50 miles and the last 50 miles.
If a = 1, b = 1 and c = 1, then the average speed of the trip is 150 / 3 = 50 miles/hr.
If a = 0.5, b = 1.5 and c = 0.5, then the average speed of the trip is 150 / ( 0.5 + 1.5 + 0.5 ) = 150/2.5 = 60 miles/hr.
Since we don't have a unique solution, E is the answer.