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Standard normal distribution question!!
assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation 20. Find P15, which is the IQ score separating the bottom 15% from the top 85%.
how do i find this!
 one year ago
 one year ago
Standard normal distribution question!! assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation 20. Find P15, which is the IQ score separating the bottom 15% from the top 85%. how do i find this!
 one year ago
 one year ago

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CliffSedgeBest ResponseYou've already chosen the best response.0
You're looking for the 15th percentile. You need to find the zscore corresponding to a proportion/probability of 0.1500, then use the zscore formula to solve for x.
 one year ago

CliffSedgeBest ResponseYou've already chosen the best response.0
This site is rather good for straightforward notes and formulas: http://stattrek.com/probabilitydistributions/standardnormal.aspx?Tutorial=Stat
 one year ago

CliffSedgeBest ResponseYou've already chosen the best response.0
dw:1349413921591:dw
 one year ago

CliffSedgeBest ResponseYou've already chosen the best response.0
Here's a Ztable if you need it: http://www.math.unb.ca/~knight/utility/NormTble.htm
 one year ago

hmdp4Best ResponseYou've already chosen the best response.0
i still dont understand.
 one year ago

CliffSedgeBest ResponseYou've already chosen the best response.0
Do you have a calculator with an inverse normal function?
 one year ago

CliffSedgeBest ResponseYou've already chosen the best response.0
If not, you'll need to use that ztable that I linked to. Find the P=0.1500 in the body of the table and read across to the margins to find the associated Zscore. Sometimes you have to estimate between two values and pick the closest one. follow the stattrek.com link to get the zscore formula, plug in your z, µ, and σ, and solve for x.
 one year ago
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