GMAT Club World Cup 2022 (DAY 9): There are several renowned Athletics

What do we know? - The premise:
> There are several renowned Athletics clubs in the city of Sportsville.
> It is a common practice in Sportsville that the athletes change clubs frequently, some every year.
> This year several sprinters have left the club Acerunners.
> However the manager of Acerunners claims that not only is the number of sprinters joining the club this year higher than those leaving,
> but also is the average speed of the athletes who joined higher than the average speed of all the sprinters of the club.

What has the author concluded? - The conclusion:
it can be concluded that the average speed of the sprinters at Acerunners has risen this year

What is the logical jump? - The assumption:
The outgoing athletes' average speed was lower than the average speed of the incoming ones.

Let's analyse the options:


Irrelevant. Why do we care about the sprinters of the adjacent city?


This won't help us conclude that the average speed of the club has risen this year. Hence, incorrect


This can happen if the outgoing sprinters retired or if the outgoing sprinters joined an underdog club which has sprinters with very low average speeds. We can't conclude anything about Acerunners' average speed this year.


Okay so the outgoing sprinters were slower than the ones who stayed. (A < B)
And the ones who stayed are slower than the incoming sprinters (B < C)
Therefore, we can conclude that A < C.
And thus, we can safely say that the average speed has risen this year.


We are concerned about the average speed here. Individual speeds won't help our case.


Hence, option D is the correct answer.

Premise :
There are several renowned Athletics clubs in the city of Sportsville. It is a common practice in Sportsville that the athletes change clubs frequently, some every year. This year several sprinters have left the club Acerunners

IC :
The manager of Acerunners claims that not only is the number of sprinters joining the club this year higher than those leaving, but also is the average speed of the athletes who joined higher than the average speed of all the sprinters of the club

Conclusion :
Therefore it can be concluded that the average speed of the sprinters at Acerunners has risen this year.

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city. irrelevant
B. This year many athletes leaving Acerunners retired from Athletics permanently. irrelevant
C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville. no information about sprinter speed comparison
D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners. this is valid and does strengthens the conclusion , if more sprinters left who were slow and more than those who left have joined and there avg speed is high then this supports the conclusion
E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year. sprinters club it is not marathon runners

OPTION D is correct

Statement, which support the possibility that sprinters who left Acerunners had an average sped less than or equal to the rest of the sprinter at Acerunners, will strongly strengthens the above conclusion

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city: Irrelevant. Reject
B. This year many athletes leaving Acerunners retired from Athletics permanently: Irrelevant. Reject
C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville: Irrelevant. Reject
D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners: Support the conclusion. Correct answer
E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year: It's weakening the conclusion. Reject

Premise:
1. Several sprinters have left the club Acerunners.
2. the number of sprinters joining the club this year higher than those leaving,
3. the average speed of the athletes who joined higher than the average speed of all the sprinters of the club.

Conclusion: Therefore it can be concluded that the average speed of the sprinters at Acerunners has risen this year.

To find the statement that most strongly strengthens the above conclusion.
Analysis: The argument will be strengthened if the speed of runners who left the club was lower than the avg speed of the club.

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city.
--> Incorrect: Irrelevant, as the conclusion only argues about avg speed of sprinters in Acerunners, a club in Sportsville.

B. This year many athletes leaving Acerunners retired from Athletics permanently.
--> Incorrect: It is still possible that the sprinters who left or retired from the club had so high average speed that even with addition of new team members the average did not rise.

C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville.
--> Incorrect: It is still possible that the sprinters who left from the club had so high average speed that even with addition of new team members the average did not rise.

D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners.
--> Correct: It is still possible that the sprinters who left or retired from the club had so high average speed that even with addition of new team members the average did not rise.

E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year.
--> Incorrect: This statement claims about only few new marathon runners. Also, if the avg speed of runners who left the club was very high then addition of these new runners might not be sufficient to increase the avg speed of the club.

heh, "most strongly strengthens".

I don't love the wording of this problem. There's enough context here—especially with that "also", there (boldfaced)—to determine that this and this are two references to the same group of athletes. By using two different wordings for the same specific group, though, this problem violates GMAC's own conventions for CR problem writing. Not good. (When GMAC includes two references to the same specific detail in a CR problem, they're scrupulous about using the same words both times.)


In problems like this one—basically, statistics problems couched in very wordy words—it's alws a good idea to extract the statistical findings from the paragraph in order to consider them more easily.

The statistical findings here are:
• Some sprinters left the club. Some others joined—more than the # who left.
• The NEW (just joined) sprinters are FASTER than the club average. <— Isolating this fact makes it VERY plain that we DON'T yet have the corresponding fact about the group who left!

Well yeah... let's go to the choices and look for that OTHER corresponding fact we want—Were the sprinters who LEFT the club SLOWER than average?

D says exactly this. Answer is D. Done and dusted.


.

BTW
This problem really needs work... There's also a second violation of GMAC's best practices here, in that the correct answer actually completes a rigorous PROOF of the given conclusion.
That contradicts the wording of the question ("most strongly..."). GMAC doesn't write sloppy problems like this; if a problem's conclusion is rigorously proved, there will not be any hedging language like "best" or "most strongly" that's only sensible in arguments whose conclusion is NOT rigorously proved.

There are several renowned Athletics clubs in the city of Sportsville. It is a common practice in Sportsville that the athletes change clubs frequently, some every year. This year several sprinters have left the club Acerunners. However the manager of Acerunners claims that not only is the number of sprinters joining the club this year higher than those leaving, but also is the average speed of the athletes who joined higher than the average speed of all the sprinters of the club. Therefore it can be concluded that the average speed of the sprinters at Acerunners has risen this year.

Which of the following statements most strongly strengthens the above conclusion?

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city.
Claim is related to club acerunner and not Sportsville city.
B. This year many athletes leaving Acerunners retired from Athletics permanently.
Whether the retire ones are sprinter or not? Also if the retired ones are sprinter with high speeds than it will weaken the conclusion.
C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville.
It may be due to other clubs average speed of sprinters has come down, hence the acerunners has highest average among all the clubs without an increase in average speed.
D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners.
Sprinter who left were slower, sprinter who joins has speed higher than the average speed. Thus resultant average speed will be increased. Suppose for 3 sprinter having speed 10mph,20mph,30mph average is 20mph. If in place of 10mph a new sprinter of 13mph joins, so the new average will be 21mph. Increase in average speed by 1mph.
E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year.
Conclusion is based on sprinter and not on marathon runners.

Hence D.

There are several renowned Athletics clubs in the city of Sportsville.
It is a common practice in Sportsville that the athletes change clubs frequently, some every year.
This year several sprinters have left the club Acerunners.
However the manager of Acerunners claims that not only is the number of sprinters joining the club this year higher than those leaving, but also is the average speed of the athletes who joined higher than the average speed of all the sprinters of the club.

Conclusion: - Therefore it can be concluded that the average speed of the sprinters at Acerunners has risen this year.

Which of the following statements most strongly strengthens the above conclusion?


We are NOT concerned with sprinters in adjacent city
Incorrect

The average speed of the sprinters at Acerunners will rise this year, if average speed of sprinters joining will be more than the average speed of sprinters retiring. It does not matter whether they retire permanently or not.
Incorrect

We are NOT concerned with all the clubs in Sportsville.
Incorrect

The average speed of the sprinters at Acerunners will rise this year, if average speed of sprinters joining will be more than the average speed of sprinters retiring. It is already mentioned that the average speed of the athletes who joined was higher than the average speed of all the sprinters of the club. If sprinters who left Acerunners were on an average slower than the sprinters of Acerunners, then average speed of sprinters will rise this year.
Correct

We are NOT concerned with marathon runners.
Incorrect

IMO D

Conclusion: "The average speed of the sprinters at Acerunners has risen this year."

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city.
INCORRECT. Whether the average speed of sprinters in Sportsville is lower than those of adjacent cities is irrelevant to the argument.

B. This year many athletes leaving Acerunners retired from Athletics permanently.
INCORRECT. Again whether many athletes leaving Acerunners retired from athletics permanently is irrelevant to the argument.

C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville.
INCORRECT. Even, if the average speed of all sprinters at Acerunners this year is the highest among all the clubs in Sportsville, it could still be higher or lower or equal to the average speed of the sprinters at Acerunners last year.

D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners.
CORRECT. If the average speed of the sprinters who left Acerunners this year was lower that the average speed of all sprinters in Acerunners in addition to the fact that the average speed of the new sprinters who joined this year is more that average speed of all sprinters fills the gap between the premise and conclusion, and thus support the argument. Notice we can surely say the average speed of sprinters in Acerunners increased this year only by knowing both these facts.

E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year.
INCORRECT. This may be the case but even with addition of 'some' runners having average speed higher than that of all marathon runners of Acerunners, there could be others who joined Acerunners this year and have such low average speed such that average speed of all runners in Acerunners this year is lower than that of last year.

There are several renowned Athletics clubs in the city of Sportsville. It is a common practice in Sportsville that the athletes change clubs frequently, some every year. This year several sprinters have left the club Acerunners. However the manager of Acerunners claims that not only is the number of sprinters joining the club this year higher than those leaving, but also is the average speed of the athletes who joined higher than the average speed of all the sprinters of the club. Therefore it can be concluded that the average speed of the sprinters at Acerunners has risen this year.

Which of the following statements most strongly strengthens the above conclusion?

[color=#0000ff]The conclusion that 'the average speed of the sprinters at Acerunners has risen this year' can become true only if the athletes joining the Acerunners have higher average speed vis-a-vis those leaving the Acerunners.[/color]

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city.
Irrelevant, since stimulus not concerned with the comparison of average speed of sprinters for different clubs in Sportsville.

B. This year many athletes leaving Acerunners retired from Athletics permanently.
Additional information. neither strengthens nor weakens

C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville.
Out of scope..similar to option A..here stimulus not concerned with the comparison of average speed of sprinters for different clubs in Sportsville.

D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners.
Correct option..because If this is true, net effect of sprinters leaving and thos joining will be positive..hence the conclusion will be strengthened

E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year.
'Some' runners may not contribute to a firm conclusion about overall rise in average speed

Correct option is (D)

ANSWER D

Conclusion: the average speed of the sprinters at Acerunners has risen this year
Premise: several sprinters have left the club Acerunners. but more sprinters joined; also those who joined have higher speed than the average speed of all the sprinters of the club


A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city. Adjacent city comparison is irrelevant here
B. This year many athletes leaving Acerunners retired from Athletics permanently. Retirement has nothing to do with the conclusion
C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville. Inter club comparison is irrelevant here
D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners. CORRECT, slower runners replaced by faster runners
E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year. Out of focus. We don't care about a new group of marathon runners

Information: Several clubs in Sportsville and atheletes change clubs often, sometimes each year. This year, sprinters left Acerunners but more joined than the number who left and the average of those who joined is higher than the average of the entire group. Therefore it means average speed of sprinters has increased this year
We need to strengthen this conclusion. Let us examine the options

A. The average speed of the sprinters in Sportsville is lower than those of the adjacent city.
We are only concerned with average speed of Acerunners in Sportsville, not of any adjacent city. ELIMINATE

B. This year many athletes leaving Acerunners retired from Athletics permanently.
Again, it is irrelevant as we need to determine what supports average speed of all sprinters in Acerunners has increased. ELIMINATE

C. The average speed of all the sprinters at Acerunners this year is the highest among all the clubs in Sportsville.
It could be highest among all clubs but this does not tell us if after the outgoings and incomings, has the average speed of sprinters increased or not. ELIMINATE

D. The sprinters who left Acerunners were on an average slower than the sprinters of Acerunners.
YES! Sprinters who left were slower on average and those who joined were faster on average than the sprinters who stayed. This clearly strengthens that overall average speed increased. ANSWER

E. Some new marathon runners whose average speed is higher than that of all the marathon runners of Acerunners joined the club this year.
We are concerned with sprinters, not marathon runners. ELIMINATE

Answer - D