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syashveersingh
What if the speed was different in the 2nd and 3rd hour? Wouldnt that change the average speed?

All we needed to find the average speed was the distance, which from statement (1) turned out to be 180 kilometers. So, no, we are not concerned about the average speed during 2nd or 3rd hours.
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Bunuel
syashveersingh
What if the speed was different in the 2nd and 3rd hour? Wouldnt that change the average speed?

All we needed to find the average speed was the distance, which from statement (1) turned out to be 180 kilometers. So, no, we are not concerned about the average speed during 2nd or 3rd hours.

I still fail to understand
average speed of 1st hour was 60 not entire trip (which we need to find)
first - 60
second - 45
third 15
average speed changes!

Why 2nd & 3rd hour are not important?
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Bunuel
syashveersingh
What if the speed was different in the 2nd and 3rd hour? Wouldnt that change the average speed?

All we needed to find the average speed was the distance, which from statement (1) turned out to be 180 kilometers. So, no, we are not concerned about the average speed during 2nd or 3rd hours.

I still fail to understand
average speed of 1st hour was 60 not entire trip (which we need to find)
first - 60
second - 45
third 15
average speed changes!

Why 2nd & 3rd hour are not important?


The important message in statement 1 is not that the average speed of the first hour was 60.
It's that 60km is one third of the total distance covered in 3hrsm so that the total distance is 180km.
Hence the avg speed is the total distance 180 divided by the total time, 3 hours.
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We only consider to calculate the average speeds when we have changing speeds in different parts of trip.
Here in statement 1 , if the answer is correct . It is assumed that the speed is constant through out the trip.
It is no where mentioned that the entire trip is made at a constant speed!!
I know we can calculate distance from st1 . But, we don't know the speed maintained in rest of the trip.


Please explain . There is no clarity.
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We only consider to calculate the average speeds when we have changing speeds in different parts of trip.
Here in statement 1 , if the answer is correct . It is assumed that the speed is constant through out the trip.
It is no where mentioned that the entire trip is made at a constant speed!!
I know we can calculate distance from st1 . But, we don't know the speed maintained in rest of the trip.


Please explain . There is no clarity.

The speed is not assumed to be constant. From (1) we know that in 1 hour the bus finished 1/3 of the distance at an average speed of 60 kilometers per hour. This implies that 60 kilometers is 1/3 of the distance, so the total distance is 180 kilometers.
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I think this is a high-quality question and I agree with explanation.
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I think this is a high-quality question and I don't agree with the explanation. While solving 1st option , total time is not mentioned. Therefore, how can we calculate the average speed for the entire journey??
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I think this is a high-quality question and I don't agree with the explanation. While solving 1st option , total time is not mentioned. Therefore, how can we calculate the average speed for the entire journey??

From (1) we know that in 1 hour the bus finished 1/3 of the distance at an average speed of 60 kilometers per hour. This implies that 60 kilometers is 1/3 of the distance, so the total distance is 180 kilometers.
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I have edited the question and the solution by adding more details to enhance its clarity. I hope it is now easier to understand.
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Bunuel

sumitsingh18
I think this is a high-quality question and I don't agree with the explanation. While solving 1st option , total time is not mentioned. Therefore, how can we calculate the average speed for the entire journey??
From (1) we know that in 1 hour the bus finished 1/3 of the distance at an average speed of 60 kilometers per hour. This implies that 60 kilometers is 1/3 of the distance, so the total distance is 180 kilometers.
Bunuel

This is the question I'm seeing: If a bus took three hours to travel from town A to town B, what was its average speed throughout the entire journey?

The question asks for average speed of entire journey. But your answer and explanation is about finding the total distance of the journey. There seems to be some confusion in the question & explanation. Please clarify.
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Bunuel

sumitsingh18
I think this is a high-quality question and I don't agree with the explanation. While solving 1st option , total time is not mentioned. Therefore, how can we calculate the average speed for the entire journey??
From (1) we know that in 1 hour the bus finished 1/3 of the distance at an average speed of 60 kilometers per hour. This implies that 60 kilometers is 1/3 of the distance, so the total distance is 180 kilometers.
Bunuel

This is the question I'm seeing: If a bus took three hours to travel from town A to town B, what was its average speed throughout the entire journey?

The question asks for average speed of entire journey. But your answer and explanation is about finding the total distance of the journey. There seems to be some confusion in the question & explanation. Please clarify.
­Please re-read the very first sentrence of the solution:

If a bus took three hours to travel from town A to town B, what was its average speed throughout the entire journey?

To find the average speed, we use the formula: \(\text{Average speed}=\frac{\text{total distance}}{\text{total time}}\). We know the total time is 3 hours, so we need to determine the total distance.

(1) In the first hour, the bus covered \(\frac{1}{3}\) of the total distance at an average speed of 60 kilometers per hour.

Since \(\frac{1}{3}\) of the distance is \(1*60=60\) kilometers, the total distance is \(3*60=180\) kilometers. This statement is sufficient.

(2) During the second hour, the bus had an average speed of 80 kilometers per hour, which is double its speed in the third hour.

During the second hour, the bus covered 80 kilometers, and during the third hour, the bus covered \(\frac{80}{2}=40\) kilometers. Thus, in the last two hours, it covered a total of 120 kilometers. However, we don't know how many kilometers were covered during the first hour, so this statement is not sufficient.


Answer: A­
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No, it would not, because you have covered 1/3 of the distance in 1 hour, and you know the speed for that hour. so if youve traved 60 kilometers in 1 hour, and that is 1/3 the distance, you know the total distance will be 3*60 =180. total distance =180 and total time is given as 3 hours. this is sufficient to find the average speed.

syashveersingh
What if the speed was different in the 2nd and 3rd hour? Wouldnt that change the average speed?
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This is a great question!!
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