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Vocab
Z or t?
Margin of Error
CI
Whatevs
100
This can be found by dividing the population standard deviation by the square root of the sample size.
Standard Error
100
What statistic MUST be present in order for me to use a Z-distribution to form a confidence interval?
Population standard deviation
100
Which two do I need to find Margin of Error: point estimate, critical value, standard error, population size.
critical value and standard error
100
If (99.8, 104.6) is a 90% confidence interval for a sample of basketball fifteen scores, what can you say about the average scores of the population?
That you are 90% sure your interval contains the population mean.
100
What is the critical Z-value for a 95% confidence interval
1.96
200
This is the singular best guess at estimating a population parameter.
Point Estimate
200
Which of these changes when I use a t-distribution as opposed to a Z-distribution: Sample size, confidence level, or critical value?
critical value
200
If the standard error of a sample is 2.3 and the critical value for a confidence level is 3.456, what is the margin of error?
7.9488
200
How old is Chelsea?
5
200
If my sample size is 12, how many degrees of freedom are there?
11
300
This is built around a point estimate in an effort to better approximate a population parameter.
Confidence Interval
300
Should I use a t-distribution or a z-distribution? Suppose that you want to find out the average weight of all players on the football team at a particular College. You are able to select ten players at random and weigh them. The mean weight of the sample of players is 198 lbs, with a standard deviation of 11.50 lbs.
t
300
Find the Margin of Error for a 95% confidence interval with a standard error of 4.2
8.232
300
The average heights of a random sample of 400 people from a city is 1.75 m. It is known that the heights of the population are random variables that follow a normal distribution with a standard deviation of 0.4 m. Determine the interval of 95% confidence for the average heights of the population.
n = 400 x = 1.75 σ = 0.4 c = 0.95 z* = 1.96 (1.75 ± 1.96 • 0.4/20 ) → (1.7108, 1.7892)
300
If my t-value is 2.518, what is the required confidence level and sample size?
C=0.99 or 99%; n=22
400
This is added and subtracted from the point estimate in order to construct a confidence interval
Margin of Error
400
Should I use a t-distribution or Z? The average heights of a random sample of 400 people from a city is 1.75 m. It is known that the heights of the population are random variables that follow a normal distribution with a standard deviation of 0.4 m. Determine the interval of 95% confidence for the average heights of the population.
Z
400
What is the margin of error for a sample with a critical value of 1.76, a sample size of 64, and a sample standard deviation of 3.5?
0.77
400
Suppose that you want to find out the average weight of all players on the football team at a particular College. You are able to select ten players at random and weigh them. The mean weight of the sample of players is 198 lbs, with a standard deviation of 11.50 lbs. Construct a 90 percent confidence interval for the population weight, if you presume the players' weights are normally distributed.
We are 90 percent confident that the true population mean of football player weights is between 192 and 204 pounds.
400
Why are confidence intervals necessary?
Because the point estimate is not a very good approximation for the population parameter.
500
This is the number of free choices allowed by my parameter.
Degrees of freedom
500
When could I use EITHER a Z-distribution or a t-distribution
When sample size is bigger than 30. With that many degrees of freedom, the t-distribution is approximately normal.
500
If the margin of error of a sample is 3.45, the sample size if 16, and the critical value for the confidence level is 1.876, then what is sample standard deviation?
7.356
500
If a sample of 36, has a mean of 29, and a standard deviation of 4.3, find a 90% confidence interval for the population mean.
(28.055,29.945)
500
DAILY DOUBLE: What is the meaning of life?
42