Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Nov 2211:00 AM IST
-01:00 PM IST
Do RC/MSR passages scare you? e-GMAT is conducting a masterclass to help you learn – Learn effective reading strategies Tackle difficult RC & MSR with confidence Excel in timed test environment- Nov 23
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. 
Nov 2510:00 AM EST
-11:00 AM EST
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors.
18 Jul 2024, 07:00
Kudos
Bookmarks
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
58% (02:02) correct
42%
(02:13)
wrong
based on 297
sessions
History
Date
Time
Result
Not Attempted Yet
Train A and Train B each departed simultaneously from Liverpool heading to London, which is 300 kilometers away. When Train A reached the destination, Train B still had 80 kilometers left to cover. What was Train A's average speed during this journey?
(1) During the first hour, Train B covered 40 kilometers less than Train A.
(2) Train B's average speed for the first 110 kilometers was 110 kilometers per hour.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked.
C. BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient to answer the question asked.
D. EACH statement ALONE is sufficient to answer the question asked.
E. Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.
(1) During the first hour, Train B covered 40 kilometers less than Train A.
(2) Train B's average speed for the first 110 kilometers was 110 kilometers per hour.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked.
C. BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient to answer the question asked.
D. EACH statement ALONE is sufficient to answer the question asked.
E. Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.
|
18 Jul 2024, 08:00
Kudos
Bookmarks
Train A and Train B each departed simultaneously from Liverpool heading to London, which is 300 kilometers away. When Train A reached the destination, Train B still had 80 kilometers left to cover. What was Train A's average speed during this journey?
Essentially, we are given that Train A covered 300 kilometers in the same time Train B covered 220 kilometers and are asked to find the average speed of Train A during this 300-kilometer trip.
(1) During the first hour, Train B covered 40 kilometers less than Train A.
Don't fall into the trap of assuming the trains maintained the same constant speed throughout their journey. If that were true, then we could reason that in the first hour, Train B fell behind by 40 kilometers. Therefore, to fall behind by 80 kilometers, it would need 2 hours, which would mean that Train A covered 300 kilometers in 2 hours, making its average speed equal to 300/2 = 150 kilometers per hour. However, this would not be correct because we cannot assume constant speed. It's possible, for example, that in the first hour, Train B covered 110 kilometers and Train A covered 150 kilometers. After that, they could have slowed down, and Train A could have covered the remaining 150 kilometers in 2 hours, spending a total of 3 hours on the journey and making its average speed equal to 300/3 = 100 kilometers per hour. Not sufficient.
(2) Train B's average speed for the first 110 kilometers was 110 kilometers per hour.
Again, don't fall into the trap of assuming the trains maintained the same constant speed throughout their journey. If that were true, then we could reason that Train B covered 220 kilometers in 2 hours, which would mean that Train A covered 300 kilometers in 2 hours, making its average speed equal to 300/2 = 150 kilometers per hour. However, this would not be correct because we cannot assume constant speed. It's possible, for example, that in the first hour, Train B covered 110 kilometers and Train A covered 150 kilometers. After that, they could have slowed down, and Train A could have covered the remaining 150 kilometers in 2 hours, spending a total of 3 hours on the journey and making its average speed equal to 300/3 = 100 kilometers per hour. Therefore, Statement 2 is not sufficient.
(1) + (2) We can use the same example as above: the average speed of Train A can be 150 kilometers per hour, assuming constant speeds for both trains, or some other speed, for example, 100 kilometers per hour if in the first hour Train B covered 110 kilometers and Train A covered 150 kilometers, and after that they slowed down and Train A covered the remaining 150 kilometers in 2 hours, spending a total of 3 hours on the journey and making its average speed equal to 300/3 = 100 kilometers per hour. Therefore, even together, the statements are not sufficient.
Answer: E.
GMAT Club Official Explanation:
Train A and Train B each departed simultaneously from Liverpool heading to London, which is 300 kilometers away. When Train A reached the destination, Train B still had 80 kilometers left to cover. What was Train A's average speed during this journey?
Essentially, we are given that Train A covered 300 kilometers in the same time Train B covered 220 kilometers and are asked to find the average speed of Train A during this 300-kilometer trip.
(1) During the first hour, Train B covered 40 kilometers less than Train A.
Don't fall into the trap of assuming the trains maintained the same constant speed throughout their journey. If that were true, then we could reason that in the first hour, Train B fell behind by 40 kilometers. Therefore, to fall behind by 80 kilometers, it would need 2 hours, which would mean that Train A covered 300 kilometers in 2 hours, making its average speed equal to 300/2 = 150 kilometers per hour. However, this would not be correct because we cannot assume constant speed. It's possible, for example, that in the first hour, Train B covered 110 kilometers and Train A covered 150 kilometers. After that, they could have slowed down, and Train A could have covered the remaining 150 kilometers in 2 hours, spending a total of 3 hours on the journey and making its average speed equal to 300/3 = 100 kilometers per hour. Not sufficient.
(2) Train B's average speed for the first 110 kilometers was 110 kilometers per hour.
Again, don't fall into the trap of assuming the trains maintained the same constant speed throughout their journey. If that were true, then we could reason that Train B covered 220 kilometers in 2 hours, which would mean that Train A covered 300 kilometers in 2 hours, making its average speed equal to 300/2 = 150 kilometers per hour. However, this would not be correct because we cannot assume constant speed. It's possible, for example, that in the first hour, Train B covered 110 kilometers and Train A covered 150 kilometers. After that, they could have slowed down, and Train A could have covered the remaining 150 kilometers in 2 hours, spending a total of 3 hours on the journey and making its average speed equal to 300/3 = 100 kilometers per hour. Therefore, Statement 2 is not sufficient.
(1) + (2) We can use the same example as above: the average speed of Train A can be 150 kilometers per hour, assuming constant speeds for both trains, or some other speed, for example, 100 kilometers per hour if in the first hour Train B covered 110 kilometers and Train A covered 150 kilometers, and after that they slowed down and Train A covered the remaining 150 kilometers in 2 hours, spending a total of 3 hours on the journey and making its average speed equal to 300/3 = 100 kilometers per hour. Therefore, even together, the statements are not sufficient.
Answer: E.
General Discussion
18 Jul 2024, 07:37
Kudos
Bookmarks
Given: Train A and Train B each departed simultaneously from Liverpool heading to London, which is 300 kilometers away. When Train A reached the destination, Train B still had 80 kilometers left to cover.
Asked: What was Train A's average speed during this journey?
Train A
Distance = 300 km
Let Average Speed = x km/hr
Time Required = 300/x hrs
Train B
Distance = 300 - 80 = 220 km
Time taken = 300/x hrs
Average Speed = 220/(300/x) = 11x/15 km/hr
(1) During the first hour, Train B covered 40 kilometers less than Train A.
During the first hours, Train B covered distance less than A = x - (11x/15) = 4x/15 = 40
x = 40*15/4 = 150 km/hrs
Train A's average speed during this journey = x = 150 km/hr
SUFFICIENT
(2) Train B's average speed for the first 110 kilometers was 110 kilometers per hour.
Since it is NOT mentioned that trains were moving at constant speeds.
Train B's avereage speed for total 220 km can not be ascertained which is 11x/15 km/hr
Therefore, Train A's average speed during this journey can not be derived.
NOT SUFFICIENT
IMO A
Asked: What was Train A's average speed during this journey?
Train A
Distance = 300 km
Let Average Speed = x km/hr
Time Required = 300/x hrs
Train B
Distance = 300 - 80 = 220 km
Time taken = 300/x hrs
Average Speed = 220/(300/x) = 11x/15 km/hr
(1) During the first hour, Train B covered 40 kilometers less than Train A.
During the first hours, Train B covered distance less than A = x - (11x/15) = 4x/15 = 40
x = 40*15/4 = 150 km/hrs
Train A's average speed during this journey = x = 150 km/hr
SUFFICIENT
(2) Train B's average speed for the first 110 kilometers was 110 kilometers per hour.
Since it is NOT mentioned that trains were moving at constant speeds.
Train B's avereage speed for total 220 km can not be ascertained which is 11x/15 km/hr
Therefore, Train A's average speed during this journey can not be derived.
NOT SUFFICIENT
IMO A
