pdf Think of probabilities as Area Under a...

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Normal Distr 1 May 13, 2013 Oct 169:45 AM Look at probabilities assigned to continuous variables. Probability Density Functions Normal Probability Density Function The "Empirical Rule" 68, 95, 99.7 Standardizing variables Using Standard Normal tables Inverse Normal Calculations Oct 169:52 AM Look at probabilities assigned to continuous variables. Probability of an exact value = Probability of an interval = Probability Density Functions 1 0 pdf 10 50 pdf Think of probabilities as "Area Under a Curve"

Transcript of pdf Think of probabilities as Area Under a...

Page 1: pdf Think of probabilities as Area Under a Curvecf.linnbenton.edu/mathsci/math/lewisr/upload/Normal... · 2013. 5. 13. · Normal Distribution Table Finding Proportions using a Normal

Normal Distr

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May 13, 2013

Oct 16­9:45 AM

Look at probabilities assigned to continuous variables.

Probability Density Functions

Normal Probability Density Function

The "Empirical Rule" ­ 68, 95, 99.7

Standardizing variables 

Using Standard Normal tables

Inverse Normal Calculations

Oct 16­9:52 AM

Look at probabilities assigned to continuous variables.

Probability of an exact value = 

Probability of an interval = 

Probability Density Functions  

10

pdf

10 50

pdf

Think of probabilities as "Area Under a Curve"

Page 2: pdf Think of probabilities as Area Under a Curvecf.linnbenton.edu/mathsci/math/lewisr/upload/Normal... · 2013. 5. 13. · Normal Distribution Table Finding Proportions using a Normal

Normal Distr

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May 13, 2013

Oct 16­9:58 AM

105

Challenge!

What is the height of the probability density function?

What is the probability of a random value between 6 and 8?

Oct 1­3:57 PM

Along the x­axis is the number of standard deviations.

Standard Normal Distribtion

concave up

concave down

Inflection point

Normal Probability Density Function

Page 3: pdf Think of probabilities as Area Under a Curvecf.linnbenton.edu/mathsci/math/lewisr/upload/Normal... · 2013. 5. 13. · Normal Distribution Table Finding Proportions using a Normal

Normal Distr

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May 13, 2013

Oct 16­10:16 AM

Texas A&M Stats Dept

Oct 16­10:18 AM

Texas A&M Stats Dept

Page 4: pdf Think of probabilities as Area Under a Curvecf.linnbenton.edu/mathsci/math/lewisr/upload/Normal... · 2013. 5. 13. · Normal Distribution Table Finding Proportions using a Normal

Normal Distr

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May 13, 2013

Oct 11­11:03 AM

Mean height amongst women is 66 inches with a standard deviation of 3 inches.

Emperical Rule 68 ­ 95 ­ 99.7% Rule

Oct 1­3:57 PM

Standard Normal Distribtion

68 ­ 95 ­ 99.7% RuleEmperical Rule

Assume that the leaf size of a maple tree has a mean of 17 cm and a standard deviation of 4 cm.

P(x > 17)=

P(x>21) = 

P(13<x<21)=

N(17,4)

P(x<25)=

P(9 < x < 13)=

Practice Activity

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Normal Distr

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May 13, 2013

Oct 1­3:57 PM

Standard Normal Distribtion

68 ­ 95 ­ 99.7% RuleEmperical Rule

Assume that the leaf size of a maple tree has a mean of 17 cm and a standard deviation of 4 cm.

P(x > 17)=

P(x>21) = 

P(13<x<21)=

N(17,4)

P(x<25)=

P(9 < x < 13)=

Practice Activity

Oct 11­11:03 AM

Mean height amongst women is 66 inches with a standard deviation of 3 inches.

More practice??

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Normal Distr

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May 13, 2013

Oct 1­3:57 PM

Standard Normal Distribtion

The numbers along the x­axis for a Std. Normal Distr. are called?

P(z >0)

P(­1< z < 2)

P(z > ­1) P(z < 1.52)

Apr 3­7:36 AM

Normal Distribution Table

Finding Proportions using a Normal Distribution table.

P(1.96< z < 1.96)

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May 13, 2013

Oct 25­7:38 AM

Practice Using the table

Oct 25­7:38 AM

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Normal Distr

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May 13, 2013

Oct 25­7:38 AM

Oct 25­7:38 AM

Z­value = 

Example:  Assume that the leaf size of a maple tree has a mean of 17 cm and a standard deviation of 4 cm.

P(x < 15.6) =

Standardizing variables 

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Normal Distr

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May 13, 2013

Oct 25­7:38 AM

Oct 25­7:38 AM

Page 10: pdf Think of probabilities as Area Under a Curvecf.linnbenton.edu/mathsci/math/lewisr/upload/Normal... · 2013. 5. 13. · Normal Distribution Table Finding Proportions using a Normal

Normal Distr

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May 13, 2013

Oct 25­7:38 AM

Inverse Normal Calculations

Find the z­value that corresponds to the area of the lower 80%.

Find the z­value that corresponds to the area of the upper 10%.

Oct 25­7:38 AM

last one!

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May 13, 2013

Sep 30­1:20 PM

Normal Approximation to the Binomial

Suppose 1000 people have a 30% chance of having O­positive blood type.

What is the probability that 280 or less will have this blood type?

Calculate Mean and Std. Deviation

Sep 30­1:20 PM

Using a calculator!!

The Standard Normal Distribution

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May 13, 2013

Oct 25­7:44 AM

Generalizations...

Oct 25­7:40 AM

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May 13, 2013

Oct 25­7:40 AM

Oct 25­7:28 AM