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Re: In a survey, 86 high school students were randomly selected [#permalink]
Eidolons03 wrote:
If I had gotten this one wrong, I probably would have given up my plans to become a statistician!!!!!!!

The median is basically the number in a set that is right in the middle of the set. In order to find the median, you first need to WRITE THE NUMBERS IN A SET IN ASCENDING ORDER.

3 - 5 - 6 - 7 - 13 - 17 - 35

Now we need to look at the set and decide which number is in the middle. 7 is the best choice because there are exacltly 3 numbers to its right (13, 17 and 35) and 3 numbers to its left (3.5 and 6).

Qunatity B is thus 7.

The mean is the avarage of all numbers in a set. All we need to do is add all numbers together and divide the result by how many numbeers there are in the set.

3 + 5 + 6 + 7 + 13 + 17 + 35 = 86

There are 7 numbers in this set.

86/7 = 12.3

Quantity A is 12.3

Qunaity A is greater than quantity B. A is the answer.

This histogram can be a bit tricky to read so I may have gotten some of the numbers wrong.


Why are you using the set of students 3 - 5 - 6 - 7 - 13 - 17 - 35 not the set of hours ?
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Re: In a survey, 86 high school students were randomly selected [#permalink]
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Yes you are right. To answer that question must be used the values on the x axis and NOT those on the y axis

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Re: In a survey, 86 high school students were randomly selected [#permalink]
Thank you
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Re: In a survey, 86 high school students were randomly selected [#permalink]
I am not able to understand how the set 3 - 5 - 6 - 7 - 13 - 17 - 35 has been derived. Please help me here. I am Lost in the tricky histogram details.
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Re: In a survey, 86 high school students were randomly selected [#permalink]
Can someone please help with the question above?
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Re: In a survey, 86 high school students were randomly selected [#permalink]
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On trick is that the median always follow the tail and the tail goes down

The Mean must be higher than the median

A is the answer


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Re: In a survey, 86 high school students were randomly selected [#permalink]
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Here is how I solved it:
First compute the median, since that is the easiest. Since there are 86 values, the median will be the average of the 43rd and 44th value, which is contained in the set "6-10". Therefore, the median can be at least 6 and at most 10.

Now compute the minimum of the mean - by taking the lowest of each set.
The calculation is as follows: (1*14)+(35*6)+(16*11)+(16*5)+(5*21)+(4*26)+(7*31)=906
89 times 10 is 890, so if the sum is 906 - then that implies that the average is at least 10.something, which is greater than the highest value of our median (10).

Note that the above method is not great - you have to estimate the the number of people, and it is likely not very precise (for example you could estimate a value wrong and get something like 890). It is far better to remember how median and mean are affected by distribution, which would lead you to the correct solution in 20 seconds.
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