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In 1987 sinusitis was the most common chronic medical condition in the Updated on: 10 Nov 2020, 07:47
Originally posted by GMATNinja on 07 Nov 2020, 10:42.
Last edited by GMATNinjaTwo on 10 Nov 2020, 07:47, edited 1 time in total.
replacing mistaken original
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Bezzerk
For option C, I could argue that people who had sinusitis in 1987 were more evenly spread out. now In 2000 people with lower ages were the ones affected more than the older ones so eventually the average could remain same or even decrease.

The premise doesn't mention anything about Sinusitis being even spread out it only mentions the incidence rates.

Can somebody shed light on where I am going wrong with my reasoning.
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Take a closer look at (C):

Quote:
C. The average age of people suffering from sinusitis will increase between 1987 and 2000.
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The passage indicates that the incidence rate for sinusitis is the same for people of all ages. So, if, for example, 10% of the population currently suffers from sinusitis, then that rate of infection will remain the same for every age group.

Because the 10% infection rate of sinusitis is evenly distributed across the age range of the population, the average age of those with sinusitis should be around the average age of the population. In other words, the average age of those with sinusitis will move with the average age of the population. Because we know that the average age of the US population will increase between 1987 and 2000, we can conclude that the average age of those with sinusitis will also increase, and (C) is correct.

I hope that helps!
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In 1987 sinusitis was the most common chronic medical condition in the 28 Jun 2021, 04:06
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Average age = Sum of the ages of each demographic / Total no. of people

Average age increases = Implies that all demographic moves ahead / ages

Therefore the argument will still hold good that for people suffering from sinusitis, the average age will increase.

Option (C) : Answer

Other Options : Indeterminable / Irrelevant
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In 1987 sinusitis was the most common chronic medical condition in the 22 May 2022, 04:28
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KarishmaB Ma'am,

Please help me understand some basics in this question.

The incidence rate of S is same for all age groups. This means that S can occur to any person from ages 5 to 55.
The incidence rate of A and BP increases with age. This means that as the person's age increases then the incidence of A and BP increases. In other words, a person aged 5 to 20 might not develop A and Bp, but a person aged 55 will definitely do.
Is the above correct?

Hence, from the above how did you draw a correlation that average age of people suffering from S is same as the average age of the population? I am not understanding this part.

Please explain a bit in detail.
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In 1987 sinusitis was the most common chronic medical condition in the 23 May 2022, 21:46
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KarishmaB Ma'am,

Please help me understand some basics in this question.

The incidence rate of S is same for all age groups. This means that S can occur to any person from ages 5 to 55.
The incidence rate of A and BP increases with age. This means that as the person's age increases then the incidence of A and BP increases. In other words, a person aged 5 to 20 might not develop A and Bp, but a person aged 55 will definitely do.
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It is about probabilities. A person aged 5 to 20 will have a low probability of developing A or Bp but aged 55 will have a higher probability of developing them.

If incidence of S is the same for all age groups, it means in the set of people who have S, there will be people of all age groups. For every age, the probability is the same.

So the set of people who have S will be a sample of the population without any age bias. If there is a 20% incidence rate of S (same for all age groups) and there is a population of 100 people (20 children, 30 youth, 30 adults, 20 old), the set of people with S will likely be 20 people (4 children, 6 youth, 6 adults, 4 old). So the average age of this set of people will be similar to the average age of the population.

In contrast, note that average age of set of people having A or Bp will be higher since incidence of these diseases is higher among the older people.
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In 1987 sinusitis was the most common chronic medical condition in the 25 May 2022, 18:33
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KarishmaB Ma'am,

Quote:
So the set of people who have S will be a sample of the population without any age bias. If there is a 20% incidence rate of S (same for all age groups) and there is a population of 100 people (20 children, 30 youth, 30 adults, 20 old), the set of people with S will likely be 20 people (4 children, 6 youth, 6 adults, 4 old). So the average age of this set of people will be similar to the average age of the population.
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In this we are assuming that the age is same for all age groups. I mean the we are taking the age of children, youth, adults, and old to be the same.

Am I right?
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In 1987 sinusitis was the most common chronic medical condition in the 31 May 2022, 22:36
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KarishmaB Ma'am,

Quote:
So the set of people who have S will be a sample of the population without any age bias. If there is a 20% incidence rate of S (same for all age groups) and there is a population of 100 people (20 children, 30 youth, 30 adults, 20 old), the set of people with S will likely be 20 people (4 children, 6 youth, 6 adults, 4 old). So the average age of this set of people will be similar to the average age of the population.

In this we are assuming that the age is same for all age groups. I mean the we are taking the age of children, youth, adults, and old to be the same.

Am I right?
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You can make the data as granular as you wish to. Only for ease have I divided them into 4 groups of children, youth, adult and old. I could divide them into 100 grps of 1 yr old, 2 yr old, 3 yr old etc and still the logic remains the same.
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In 1987 sinusitis was the most common chronic medical condition in the 19 Dec 2022, 11:09
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Is inference question and derive conclusion questions the same?

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In 1987 sinusitis was the most common chronic medical condition in the 19 May 2023, 04:35
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In 1987 sinusitis was the most common chronic medical condition in the United States, followed by arthritis and high blood pressure, in that order.
The incidence rates for both arthritis and high blood pressure increase with age, but the incidence rate for sinusitis is the same for people of all ages.
The average age of the United States population will increase between 1987 and 2000.

Which of the following conclusions can be most properly drawn about chronic medical conditions in the United States from the information given above?
(A) Sinusitis will be more common than either arthritis or high blood pressure in 2000.
(B) Arthritis will be the most common chronic medical condition in 2000.
(C) The average age of people suffering from sinusitis will increase between 1987 and 2000.
(D) Fewer people will suffer from sinusitis in 2000 than suffered from it in 1987.
(E) A majority of the population will suffer from at least one of the medical conditions mentioned above by the year 2000.

I am having some difficulty in drawing conclusion questions. Please can some provide some helpful pointers to tackle such questions.. thanks.

One important point you need to understand to understand this question is the increase in average age of a population.
Lets say average age of US population is 40 yrs. (Add ages of all people and divide by the number of people). The average age need not increase with time (it can even reduce e.g. when life expectancy decreases; people live shorter lives; lots of new babies are born) If average age increases to 50 yrs, it means people are living longer lives or not many new babies are being born or both (a problem being faced by much of the developed world today)
So when we say average life increased, it is probably because there are more aged people.

Premises:
- In 1987 sinusitis most common chronic condition followed by arthritis and high blood pressure
- More arthritis and high blood pressure with age
- Incidence of sinusitis is the same for people of all ages
- Average age will increase between 1987 and 2000.

Let's refresh what we said about conclusion questions - should be implied from the argument and should give no new data.

(A) Sinusitis will be more common than either arthritis or high blood pressure in 2000.
With increase in average age, we cannot say this. It is possible that other two become more common.

(B) Arthritis will be the most common chronic medical condition in 2000.
Definitely no reason to pick Arthritis out of the two - BP and Arthritis so no need to even think about it.

(C) The average age of people suffering from sinusitis will increase between 1987 and 2000.
Since incidence of sinusitis is the same for all ages, we can conclude that the average age of a person suffering from Sinusitis is the same as the average age of the population. Since average age of population will increase, average age of people suffering from Sinusitis will also increase.

(D) Fewer people will suffer from sinusitis in 2000 than suffered from it in 1987.
Sinusitis does not depend on age so cannot be concluded.

(E) A majority of the population will suffer from at least one of the medical conditions mentioned above by the year 2000.
No reason to conclude this.
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Here- what if the the incidence of sinusitis is more common amongst the younger cohort? Would even then an increase in the average age also increase the incidence of sinusitis ? I fail to understand why is E wrong.
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In 1987 sinusitis was the most common chronic medical condition in the 27 Sep 2024, 03:33
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In this answer, do we assume that no one with sinusitis dies? I'm not able to prove it mathematically.
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In 1987 sinusitis was the most common chronic medical condition in the 01 Oct 2024, 10:56
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In this answer, do we assume that no one with sinusitis dies? I'm not able to prove it mathematically.
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We don't need to worry about that because "the incidence rate for sinusitis is the same for people of all ages". So what percent of 15-year-olds have sinusitis? X%. What percent of 62-year-olds have sinusitis? X% again! What percent of 95-year-olds? (You get the idea.)

Let's say that x = 5 (i.e. x% of people of any age have sinusitis). That number only applies to people who are alive. So if we have 100 95-year-olds, we expect 5 of them to have sinusitis. Maybe sinusitis is particularly fatal for 95-year-olds, but that doesn't matter here. For every 100 95-year-olds who are still alive, 5 of them should have sinusitis.

In other words, a particularly high fatality rate for 95-year-olds would just mean that the percentage for 95-year-olds would be much HIGHER than x% if sinusitis were NOT so fatal. Regardless of whether the fatality rate is high or low, we end up with x% at any age.

The data is what it is, and the passage isn't concerned with how we arrived at x% for each age.

Is it POSSIBLE that an average increase in the population age will somehow cause a DECREASE in the percentage of older people who have sinusitis? Sure, but based on the information in the passage, that's not what we expect to happen.

I hope that helps!
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In 1987 sinusitis was the most common chronic medical condition in the 11 Nov 2025, 04:33
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