Z-Scores
Do Z score problems use Sample Standard Deviation or Population Standard Deviation
Population Standard Deviation
What is the formula for degrees of freedom (DF)
DF= N-1
What 2 things do you use the Central Limit Theorem for?
Sample Means (Averages) and Sums
What does PDF stand for?
Probability Distribution Function
What is another common term for Error Bound (EB)?
Margin of Error
What is a point estimate?
The mean
Why wont the t score formula work in most cases if the sample size is small?
Because you normally don't know the population SD
What is the distribution for the Central Limit Theorem?
X~N(M,SD)
What are the two characteristics each discrete probability distribution function?
Each probability is between 0-1 and The sum of all the probabilities add up to 1
What do you use population proportions for?
To find the confidence interval
What is a error bound/margin of error?
A range of values above and below the point estimate
What are the four things needed in the T-score formula?
the sample mean, the sample size, the sample SD and a confidence interval
What is the Central Limit Theorem?
That the distribution of sample means approaches a normal distribution
What is the expected value?
The long term average/mean
How do you find p' and q'
p'=x/n and q'=1-p'
Why do we plus and minus in the z score formula?
To find the high and low end of the margin of error
For a 95% confidence level which is larger z score or t score?
T score (2.262)
What type of curve is a normal distribution?
A Bell Curve
What is the difference between Permutations and Combinations?
In Permutations order matters but in Combinations order is irrelevant
Name one of the two scenerios where we use population proportion
When we don't know the mean and we know the proportion of the sample that said yes
What is the confidence level?
The success rate of the method used to construct the confidence interval
Who invented the T-distribution?
William S Gosset
We took a survey of every person in Minnesota that owns a IPads age. The average age of these people was 32 and and suppose the standard deviation is 3 years. Complete the distribution.
x~N(32,3)
How many different 9 letter arrangements are possible using the letters in the word DISAPPEAR?
9!/2!*2!=90,720
If we surveyed 500 people and asked if they had a IPhone and 435 of them said yes what would p' and q' be?
p'=0.87 q'=0.13