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Bunuel
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A car travels the first one-third of the total time taken to cover a Updated on: 13 Jan 2020, 21:53
Originally posted by Bunuel on 06 Jan 2020, 07:36.
Last edited by chetan2u on 13 Jan 2020, 21:53, edited 1 time in total.
Corrected the OA
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35% (medium)

Question Stats:

74% (01:45) correct 26% (01:56) wrong based on 211 sessions

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A car travels the first one-third of the total time taken to cover a distance at a speed of 10 kmph, the next one-third of time at a speed of 20 kmph and the last one-third time at 60 kmph. Find the average speed of the car for the whole journey.

A. 18 kmph
B. 20 kmph
C. 25 kmph
D. 30 kmph
E. 40 kmph
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D
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A car travels the first one-third of the total time taken to cover a 13 Jan 2020, 21:13
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Abhishek009
Bunuel
A car travels the first one-third of the total time taken to cover a distance at a speed of 10 kmph, the next one-third of time at a speed of 20 kmph and the last one-third time at 60 kmph. Find the average speed of the car for the whole journey.

A. 18 kmph
B. 20 kmph
C. 25 kmph
D. 30 kmph
E. 40 kmph
Let the total Distance be 180 Kms

Time required to travel first 1/3rd distance is 60/10 = 6 hours
Time required to travel next 1/3rd distance is 60/20 = 3 hours
Time required to travel final 1/3rd distance is 60/60 = 1 hours

Thus, Total time taken to travel 180 Kms is 10 Hours , so Average speed is 18 Kmph, Answer must be (A)
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I have some doubt in your solution. The question mentions 1/3rd of the time, not 1/3rd of the distance.
Car travels at 10 mph for first t/3 hr ----> Distance = 10t/3
Car travels at 20 mph for first t/3 hr ----> Distance = 20t/3
Car travels at 60 mph for first t/3 hr ----> Distance = 60t/3
Hence, total distance = 90t/3 = 30t

Average velocity = total distance /total time = 30t / t = 30 kmph
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A car travels the first one-third of the total time taken to cover a 13 Jan 2020, 08:01
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Bunuel
A car travels the first one-third of the total time taken to cover a distance at a speed of 10 kmph, the next one-third of time at a speed of 20 kmph and the last one-third time at 60 kmph. Find the average speed of the car for the whole journey.

A. 18 kmph
B. 20 kmph
C. 25 kmph
D. 30 kmph
E. 40 kmph
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Let the total Distance be 180 Kms

Time required to travel first 1/3rd distance is 60/10 = 6 hours
Time required to travel next 1/3rd distance is 60/20 = 3 hours
Time required to travel final 1/3rd distance is 60/60 = 1 hours

Thus, Total time taken to travel 180 Kms is 10 Hours , so Average speed is 18 Kmph, Answer must be (A)
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A car travels the first one-third of the total time taken to cover a 13 Jan 2020, 21:56
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Bunuel
A car travels the first one-third of the total time taken to cover a distance at a speed of 10 kmph, the next one-third of time at a speed of 20 kmph and the last one-third time at 60 kmph. Find the average speed of the car for the whole journey.

A. 18 kmph
B. 20 kmph
C. 25 kmph
D. 30 kmph
E. 40 kmph
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Let the total time taken be 3x..
Distance traveled in first x hr is speed*time =10*x or 10x. Similarly next x hrs 20x and 60x.
Total distance covered =10x+20x+60x=90x
Time taken =3x
Average speed =90x/3x=30kmph

D

OA corrected from A to D
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A car travels the first one-third of the total time taken to cover a 19 Aug 2023, 23:53
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A car travels the first one-third of the total time taken to cover a distance at a speed of 10 kmph, the next one-third of time at a speed of 20 kmph and the last one-third time at 60 kmph. Find the average speed of the car for the whole journey.

Average speed = Total Distance / Total Time

Let total time be "T"

Therefore, total distance D = 10x(T/3) + 20x(T/3)+ 60x(T/3) = 30T

Average speed = Total Distance / Total Time = 30T/T = 30 kmph

Hence D
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A car travels the first one-third of the total time taken to cover a 20 Aug 2023, 00:03
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Bunuel
A car travels the first one-third of the total time taken to cover a distance at a speed of 10 kmph, the next one-third of time at a speed of 20 kmph and the last one-third time at 60 kmph. Find the average speed of the car for the whole journey.

A. 18 kmph
B. 20 kmph
C. 25 kmph
D. 30 kmph
E. 40 kmph
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When an object travels at different speeds, its average speed is the weighted average of all individual speeds with 'time taken at each speed' as the weights. Here since equal time was taken at speeds of 10, 20 and 60, the average speed will simply be the average of all 3 speeds i.e.

Average speed =\( \frac{(10 + 20 + 60)}{3} = 30\) kmph

To read up on what are the weights in weighted averages, check: https://anaprep.com/arithmetic-weights- ... d-average/
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A car travels the first one-third of the total time taken to cover a 21 Dec 2025, 21:15
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