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February 21, 2026, 07:23:43 pm
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TyErd

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question
« on: October 31, 2010, 11:55:45 am »
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The average height of a team of basketball players is 186cm with a standard deviation of 15cm.
What effect would the following have on the mean and standard deviation. (increase, decrease, same)

a) if a new member with height of exactly 186cm joined the team.
b) if a new member with height of exactly 170cm joined the team.
c) if a new member with height of exactly 200cm joined the team.

How would you go about doing these questions? Is there like a formula or something that'll make it easier.
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"Don’t ever let somebody tell you you can’t do something, not even me.  Alright?  You got a dream, you gotta protect it.  People can’t do something themselves, they wanna tell you you can’t do it.  If you want something, go get it, period." - Chris Gardner

onerealsmartass

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Re: question
« Reply #1 on: October 31, 2010, 12:09:31 pm »
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a) mean and SD would remain the same as the new player is the mean height
b) mean would be less
c) the mean would be higher
im not entirely sure of the SD of b and c
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TyErd

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Re: question
« Reply #2 on: October 31, 2010, 12:11:22 pm »
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Quote from: onerealsmartass on October 31, 2010, 12:09:31 pm
a) mean and SD would remain the same as the new player is the mean height
b) mean would be less
c) the mean would be higher
im not entirely sure of the SD of b and c

yeah that's what i have trouble with as well. I'm tryna think of it logically but its too confusing.
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"Don’t ever let somebody tell you you can’t do something, not even me.  Alright?  You got a dream, you gotta protect it.  People can’t do something themselves, they wanna tell you you can’t do it.  If you want something, go get it, period." - Chris Gardner

onerealsmartass

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Re: question
« Reply #3 on: October 31, 2010, 12:35:26 pm »
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well lets hope someone who knows how to interpret it can give us a hand.
Because it would suck if we get screwed over by similar question on the exam :/
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TyErd

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Re: question
« Reply #4 on: October 31, 2010, 12:40:15 pm »
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I know, fuck that'd be bad. Where's Martoman when you need her. hmm..
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"Don’t ever let somebody tell you you can’t do something, not even me.  Alright?  You got a dream, you gotta protect it.  People can’t do something themselves, they wanna tell you you can’t do it.  If you want something, go get it, period." - Chris Gardner

TyErd

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Re: question
« Reply #5 on: October 31, 2010, 05:55:12 pm »
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anyone have a clue how to do the standard deviation part of this question?
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"Don’t ever let somebody tell you you can’t do something, not even me.  Alright?  You got a dream, you gotta protect it.  People can’t do something themselves, they wanna tell you you can’t do it.  If you want something, go get it, period." - Chris Gardner

linahh123

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Re: question
« Reply #6 on: October 31, 2010, 06:05:49 pm »
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i got it. Any of you guys using tinspire?
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linahh123

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Re: question
« Reply #7 on: October 31, 2010, 06:08:02 pm »
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a. mean is the same, sd decreases
b. mean decrease, sd decreases
c. mean increases, sd decreases
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onerealsmartass

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Re: question
« Reply #8 on: October 31, 2010, 06:08:17 pm »
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yes i am ;)
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onerealsmartass

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Re: question
« Reply #9 on: October 31, 2010, 06:08:42 pm »
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so how do you do it?
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linahh123

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Re: question
« Reply #10 on: October 31, 2010, 06:20:34 pm »
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for this example ill be using the values: 186, 171,201.
mean=186 , one sd from the mean is achieved by adding 15 to the median and subtracting 15 for median to get 171 and 201.

go to lists and spreadsheets
in the first column type in: 171,186,201
that would give mean=186 sd=15 (check by going to stats ,stat calc, one variable,x1 is that column)

then substitute in 186 as the 4th value in the column, the values of the mean and sd should change to 186 and 12.24 respectively

b) then delete 186 and replace it with 170 so 170 is now the 4th value in the column, record the change in mean and sd. it should be 182 and 14.63 respectively.

c) repeat step b but instead use the value 200.
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meefz

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Re: question
« Reply #11 on: October 31, 2010, 06:23:09 pm »
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Quote from: linahh123 on October 31, 2010, 06:08:02 pm
a. mean is the same, sd decreases
b. mean decrease, sd decreases
c. mean increases, sd decreases
how does the sd decrease for the part c? shouldnt it increase as a height larger than the mean is added??
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linahh123

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Re: question
« Reply #12 on: October 31, 2010, 06:26:21 pm »
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if the sd=15, 200 is still within 1 standard deviation of the mean.
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linahh123

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Re: question
« Reply #13 on: October 31, 2010, 06:32:07 pm »
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Quote from: linahh123 on October 31, 2010, 06:26:21 pm
if the sd=15, 200 is still within 1 standard deviation of the mean therefore it is not extremely higher than the mean
 
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onerealsmartass

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Re: question
« Reply #14 on: October 31, 2010, 06:36:23 pm »
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oooh k sort of makes sense.
thanks for that, hope it doesnt appear on the exam...
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