# Modified Box Plot Help + Simple Standard Deviation

• Jan 20th 2011, 04:26 PM
snypeshow
Modified Box Plot Help + Simple Standard Deviation
Hey guys

so i have 3 box plot diagrams given to me:

http://img132.imageshack.us/img132/8664/a1q15.jpg

and i have to answer a few questions on it, without knowing what the actual raw data is:

1) Which one of the 3 distributions is most likely to have a mean that is greater than the median?
(my guess is C because the Interquartile Range is the biggest amongst the 3)

2) Which one has the smallest maximumn?
(my guess is A because B has outliers and C looks alot bigger)

3) Which one has the smallest value of Q3?
(my guess is A)

i just want someone to confirm if i'm right on these, thanks.

for Standard Deviation:
Consider a sample of 3 observations, with a standard deviation of s =2. If the smallest two observations are 10 and 12, what is the value of the third observation?

is 14 right? because it says 10 and 12 are the lesser of the 3 observations
• Jan 21st 2011, 11:59 PM
CaptainBlack
Quote:

Originally Posted by snypeshow
Hey guys

so i have 3 box plot diagrams given to me:

http://img132.imageshack.us/img132/8664/a1q15.jpg

and i have to answer a few questions on it, without knowing what the actual raw data is:

1) Which one of the 3 distributions is most likely to have a mean that is greater than the median?
(my guess is C because the Interquartile Range is the biggest amongst the 3)

I don't think so, think about what the histograms might look like. A distribution with positive skew will have a mean greater than the median. So which looks as though it might have the biggest skew?

CB
• Jan 22nd 2011, 12:07 AM
CaptainBlack
Quote:

Originally Posted by snypeshow
Hey guys

so i have 3 box plot diagrams given to me:

http://img132.imageshack.us/img132/8664/a1q15.jpg

and i have to answer a few questions on it, without knowing what the actual raw data is:

1) Which one of the 3 distributions is most likely to have a mean that is greater than the median?
(my guess is C because the Interquartile Range is the biggest amongst the 3)

2) Which one has the smallest maximumn?
(my guess is A because B has outliers and C looks alot bigger)

3) Which one has the smallest value of Q3?
(my guess is A)

i just want someone to confirm if i'm right on these, thanks.

I think you should revise what a box and whisker plot actually shows, your answer to 3 shows this need.

Also for Q2 you need to check what they are actually asking for, probably which has the greatest upper whisker which ignores the outliers, or are outliers to be included?

CB