Steve traveled the first 2 hours of his journey at 40 mph and the remaining 3 hours of his journey at 80 mph. What is his average speed for the entire journey?
A. 60 mph
B. 56.67 mph
C. 53.33 mph
D. 64 mph
E. 66.67 mph
The OA is D.
I'm confused by this PS question. Experts, any suggestion, please? Thanks in advance.
Steve traveled the first 2 hours of his journey...
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Speed = Distance/TimeLUANDATO wrote:Steve traveled the first 2 hours of his journey at 40 mph and the remaining 3 hours of his journey at 80 mph. What is his average speed for the entire journey?
A. 60 mph
B. 56.67 mph
C. 53.33 mph
D. 64 mph
E. 66.67 mph
The OA is D.
I'm confused by this PS question. Experts, any suggestion, please? Thanks in advance.
OR
Distance = Speed * Time
Part 1: D1 = 40*2 = 80
Part 2: D2 = 80*3 = 240
Total Distance = D1 + D2 = 80 + 240 = 320
Total Time = 2 + 3 = 5
Speed = 320/5 = 64 mph
Answer is D
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2 hours are spent at 40mph.LUANDATO wrote:Steve traveled the first 2 hours of his journey at 40 mph and the remaining 3 hours of his journey at 80 mph. What is his average speed for the entire journey?
A. 60 mph
B. 56.67 mph
C. 53.33 mph
D. 64 mph
E. 66.67 mph
3 hours are spent at 80mph.
Average speed for all 5 hours = (2*40 + 3*80)/5 = 320/5 = 64.
The correct answer is D.
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Mitch's and Dan's approach is probably simplest. But here's a fun alternative:LUANDATO wrote:Steve traveled the first 2 hours of his journey at 40 mph and the remaining 3 hours of his journey at 80 mph. What is his average speed for the entire journey?
A. 60 mph
B. 56.67 mph
C. 53.33 mph
D. 64 mph
E. 66.67 mph
The OA is D.
I'm confused by this PS question. Experts, any suggestion, please? Thanks in advance.
If Steve had spent the same amount of time traveling at each speed, his average would have been right in the middle of 40 and 80, or 60mph. We know he spent more time traveling at the faster speed, and thus, his average must be more than 60. That leaves us D and E.
Now we can test one of the two remaining choices and see if we get a 3:2 ratio in favor of time spent traveling at 80mph.
Test D: 64
Plot the rates on a number line:
406480
Gaps:2416
Ratio of time spent at 80 mph to 40 mph: 24:16 = 3:2. And we've got our answer.
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Steve's total distance was 2 x 40 + 3 x 80 = 80 + 240 = 320 miles.BTGmoderatorLU wrote:Steve traveled the first 2 hours of his journey at 40 mph and the remaining 3 hours of his journey at 80 mph. What is his average speed for the entire journey?
A. 60 mph
B. 56.67 mph
C. 53.33 mph
D. 64 mph
E. 66.67 mph
We can now determine average speed:
Average speed = (total distance)/(total time)
Average speed = 320/5 = 64 mph
Answer: D
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