Due to construction, the speed limit
along an 8-mile section of highway is
reduced from 55 miles per hour to 35
miles per hour. Approximately how
many minutes more will it take to
travel along this section of highway at
the new speed limit than it would have
taken at the old speed limit ?
(A) 5
(B) 8
(C) 10
(D) 15
(E) 24
oa is B
speed
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Its asking for an approximation. So I rounded the 55 to 60 and the 35 to 30.
So at 60 mph you are going 1 mile minute so it will take 8 minutes. At the new speed you are going 30 so it takes twice the time meaning 16. 16-8=8
i may be wrong though
So at 60 mph you are going 1 mile minute so it will take 8 minutes. At the new speed you are going 30 so it takes twice the time meaning 16. 16-8=8
i may be wrong though
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Distance = Rate * Time => Time = Distance/Speedgrandh01 wrote:Due to construction, the speed limit
along an 8-mile section of highway is
reduced from 55 miles per hour to 35
miles per hour. Approximately how
many minutes more will it take to
travel along this section of highway at
the new speed limit than it would have
taken at the old speed limit ?
(A) 5
(B) 8
(C) 10
(D) 15
(E) 24
oa is B
Time taken to cover 8 miles with the speed of 55mph = 8/55 Hrs
Time taken to cover 8 miles with the speed of 35mph = 8/35 Hrs
Difference in time = (8/35) - (8/55) hrs = 32/385 hrs = 60 * (32/385) minutes = (approx) 5 minutes.
Ans A.
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@ avada : I don't think that we can apprx it this way.
60 is double of 30 but according to actual figures, 55 is nowhere close to double of 35. If we want to get apprx values then after the approximation, the ratio of new values should be close to 55 : 35.
60 is double of 30 but according to actual figures, 55 is nowhere close to double of 35. If we want to get apprx values then after the approximation, the ratio of new values should be close to 55 : 35.
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When speed was 55 mph, time taken to cross 8 miles stretch = 8 * 60/55 = 8 * 12/11 = 96/11 = 8.72 minsgrandh01 wrote:Due to construction, the speed limit
along an 8-mile section of highway is
reduced from 55 miles per hour to 35
miles per hour. Approximately how
many minutes more will it take to
travel along this section of highway at
the new speed limit than it would have
taken at the old speed limit ?
(A) 5
(B) 8
(C) 10
(D) 15
(E) 24
oa is B
When speed was 55 mph, time taken to cross 8 miles stretch = 8 * 60/35 = 8 * 12/7 = 13.71
Difference in time = 13.71 - 8.72 = 5
The correct answer is A.
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Slower rate : faster rate = 35/55 = 7/11.grandh01 wrote:Due to construction, the speed limit
along an 8-mile section of highway is
reduced from 55 miles per hour to 35
miles per hour. Approximately how
many minutes more will it take to
travel along this section of highway at
the new speed limit than it would have
taken at the old speed limit ?
(A) 5
(B) 8
(C) 10
(D) 15
(E) 24
Rate and time are RECIPROCALS.
Since the slower rate is 7/11 of the faster rate, the time at the slower rate will be 11/7 of the time at the faster rate.
Thus, the time at the slower rate will be 4/7 LONGER than the time at the faster rate:
4/7 * 8/55 ≈ 1/2 * 1/6 ≈ 1/12.
Thus, the trip will take approximately 1/12 of an hour longer -- in other words, 5 more minutes -- at the slower rate.
The correct answer is A.
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