NandishSS wrote:Fast-food restaurants make up 45 percent of all restaurants in Cantaria. Customers at these restaurants tend to be young; in fact, studies have shown that the older people get, the less likely they are to eat in fast-food restaurants. Since the average age of the Canatrian population is gradually rising and will continue to do so, the number of fast-food restaurants is likely to decrease.

Which of the following, if true, most seriously weakens the argument?

A) Fast-food restaurants in Canatria are getting bigger, so each one can serve more customers.
B) Some older people eat at fast-food restaurants more frequently than the average young person.
C) Many people who rarely eat in fast-food restaurants nevertheless eat regularly in restaurants.
D) The overall population of Canatria is growing steadily.
E) As the population of Canatria gets older, more people are eating at home.

OA:D

Premise: The average age of the Canatrian population is gradually rising, and studies have shown that the older people get, the less likely they are to eat in fast-food restaurant.
Conclusion: The number of fast-food restaurants is likely to decrease.

One assumption is that AVERAGE = NUMBER.

Answer choice D: The overall population of Canatria is growing steadily.
Consider the following case:
Now: 60 20-year old citizens and 40 50-year old citizens, total population = 100, average age = (60*20 + 40*50)/100 = 32.
Five years from now: 400 20-year old citizens and 600 50-year old citizens, total population = 1000, average age = (400*20 + 600*50)/1000 = 38.
Here, the average age increases from 32 to 38, but the number of young people INCREASES from 60 to 400, WEAKENING the conclusion that the number of fast food restaurants catering to young people will decrease.

The correct answer is D.

GMATGuruNY wrote:

NandishSS wrote:Fast-food restaurants make up 45 percent of all restaurants in Cantaria. Customers at these restaurants tend to be young; in fact, studies have shown that the older people get, the less likely they are to eat in fast-food restaurants. Since the average age of the Canatrian population is gradually rising and will continue to do so, the number of fast-food restaurants is likely to decrease.

Which of the following, if true, most seriously weakens the argument?

A) Fast-food restaurants in Canatria are getting bigger, so each one can serve more customers.
B) Some older people eat at fast-food restaurants more frequently than the average young person.
C) Many people who rarely eat in fast-food restaurants nevertheless eat regularly in restaurants.
D) The overall population of Canatria is growing steadily.
E) As the population of Canatria gets older, more people are eating at home.

OA:D

Premise: The average age of the Canatrian population is gradually rising, and studies have shown that the older people get, the less likely they are to eat in fast-food restaurant.
Conclusion: The number of fast-food restaurants is likely to decrease.

One assumption is that AVERAGE = NUMBER.

Answer choice D: The overall population of Canatria is growing steadily.
Consider the following case:
Now: 60 20-year old citizens and 40 50-year old citizens, total population = 100, average age = (60*20 + 40*50)/100 = 32.
Five years from now: 400 20-year old citizens and 600 50-year old citizens, total population = 1000, average age = (400*20 + 600*50)/1000 = 38.
Here, the average age increases from 32 to 38, but the number of young people INCREASES from 60 to 400, WEAKENING the conclusion that the number of fast food restaurants catering to young people will decrease.

The correct answer is D.

Hi ,
Its a bit unclear to me can you explain it a bit more?

Let's start with listing all premises:

1. FF restaurants - 45% of restaurants in Cantaria
2. The older people get, lesser likely they are to eat in FF restaurants
3. Younger people eat at FF restaurants
4. Avg age of Cantarian population is rising and continuing trend

Conclusion - Number of fast food restaurants will decrease
Assumption - 1. Number of customers interested in eating at a FF restaurant will reduce
2. Number of younger people in Cantaria will reduce

Now going through the options:
A. This only strengthens the conclusion because if they are able to cater to more people, more cost but the pool of people might fall.
B. This is not directly tackling the problem of lesser people to eat at restaurants. Some exceptions will not reverse a possible trend.
C. The conclusion clearly mentions decrease in number of FF restaurants. Doesn't count.
D. Consider this: If the overall population increases, even if the average age is higher, the proportion of younger people might fall but the absolute number is likely to increase. So, in country Hakuna Matata, if there were earlier 100 people with average age 45, even if the average age increases to 55 but the overall population increases to 1000 the number of younger people would have increased. So, this is a possible situation which weakens the author's argument.
E. This only further strengthens the argument.

So, the answer should be D

ritzzzr wrote:

GMATGuruNY wrote:

NandishSS wrote:Fast-food restaurants make up 45 percent of all restaurants in Cantaria. Customers at these restaurants tend to be young; in fact, studies have shown that the older people get, the less likely they are to eat in fast-food restaurants. Since the average age of the Canatrian population is gradually rising and will continue to do so, the number of fast-food restaurants is likely to decrease.

Which of the following, if true, most seriously weakens the argument?

A) Fast-food restaurants in Canatria are getting bigger, so each one can serve more customers.
B) Some older people eat at fast-food restaurants more frequently than the average young person.
C) Many people who rarely eat in fast-food restaurants nevertheless eat regularly in restaurants.
D) The overall population of Canatria is growing steadily.
E) As the population of Canatria gets older, more people are eating at home.

OA:D

Premise: The average age of the Canatrian population is gradually rising, and studies have shown that the older people get, the less likely they are to eat in fast-food restaurant.
Conclusion: The number of fast-food restaurants is likely to decrease.

One assumption is that AVERAGE = NUMBER.

Answer choice D: The overall population of Canatria is growing steadily.
Consider the following case:
Now: 60 20-year old citizens and 40 50-year old citizens, total population = 100, average age = (60*20 + 40*50)/100 = 32.
Five years from now: 400 20-year old citizens and 600 50-year old citizens, total population = 1000, average age = (400*20 + 600*50)/1000 = 38.
Here, the average age increases from 32 to 38, but the number of young people INCREASES from 60 to 400, WEAKENING the conclusion that the number of fast food restaurants catering to young people will decrease.

The correct answer is D.

Hi ,
Its a bit unclear to me can you explain it a bit more?

The argument assumes that an increase in the average age will lead to a decrease in the number of young people frequenting fast-food restaurants.

In the case in blue:
The total population increases from 100 to 1000.
The average age increases from 32 to 38.
The total number of young people increases from 60 to 400.

This case illustrates that an increase in the total population can yield both an increase in the average age AND an increase in the total number of young people.
Thus, the OA attacks the assumption that an increase in the average age will lead to a decrease in the number of young people frequenting fast-food restaurants, thereby weakening the conclusion that the number of fast-food restaurants is likely to decline.