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10 Cards in this Set
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Imp point

Many histograms are bellshaped symmetricthese are modeled with a density curve called a normal distribution.


Characteristics of a Normal Distribution

1.Symmetric
2.Bellshaped 3.One peak 4.Mean=Median 

Notation for Normal Distribution

1.Mu=point of symmetry of normal distibution
2.Sigma=distance from the mean to the point where the curve begins to fall less steeply 3.Behind the mean we do:musigma. 4.After the mean we do:mu+sigma 

Std.dev (mu)

It is the distance from the mean(mu) to the point where the skier begins to decelerate. (see graph on CD)


Animtion of Normal Distribution of changing MU

MEAN:
1.If zero then it is symmetric 2.if mu>0 then graph moves on x axis to the right 3. If mu<0 then graph moves on x axis to the left 

Animtion of Normal Distribution of changing SIGMA

1. Increase sigma then the graph's base covers more area on the x axis and it widens
2.Decrease sigma then the graph becomes thinner 

Importance of Normal Distribution

1.Describes many distributions of real data and "chance" outcomes
2.Models many roughly sumetric distibutions for statistical inference 

Normal Distribution Areas

68% of data lies within 1 std.dev of the mean
95% of data lies within 2 std.dev of the mean 99.7% of the data lies within 3 std.dev of MEAN 

Percentage of Area within intervals

1.Subtract by previous percentage and then divide by half to get the area between tha particular interval


Cumalative Area Percentages

1.Add from left to right
2.It is the values that lie to the left of the values that the amount of percentages cover. 