Statistics questions

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Apply the applicable rule before solving any problem.  Show the formula, and graph where applicable.

 

1a) Sx  is a known estimate: True or False

 

1b) Population mean is a known estimate:  True or False

 

1c) The objective of a confidence interval is not to bracket the fixed population mean:  True or False

 

1d) T-test discusses the deviation of a random variable  from its mean measured in standard deviation of the sample mean units:  True or False

 

1e) T-test is used to test a hypothesis about the population mean: True or False

 

 

Standard Normal Probability Distribution

 

2) Find the probability that the random value of Z is between +.65 and +.2.33.

 

 

 

T distribution is symmetric and t table gives values of t such that the probability of the larger t is equal to a given probability.

 

3a) P(t > to) = 0.10 given a sample size of 13.

Find to

 

3b) P(-to  > t > + to) = 0.05 given a sample size of 9.

Find to

 

3c) P(t <  2.1098) = ? given a sample size of 18.

Find the associated probability.

 

Consider the probability that a random interval x ± (t.05)S will contain the fixed μ (population mean) is .95  That is:

 

P( – t.05S ≤  μ ≤   + t.05S) = .95.

 

4) Construct a Confidence Interval given the following:

Sample size = 10,  = 131, S= 971.11.

 

T test:

5) If a real estate market is strong, there will be a close relationship between the asking price for homes and the selling price.  Suppose that one analyst believes that the mean difference between asking price and selling price for homes in a particular market area is less than $2000.  To test this using an alpha level equal to .05, random sample of n=15 homes that have sold recently was selected.  The difference between asking price and selling price data from the sample is in the following:

 

$2053 $1693 $1854 $1747 $869
$1396 $2473 $1931 $2303 $1502
$1038 $2755 $2084 $1664 $2104

 

What should we conclude about the analysts claim?  Solve the test statistic approach.  Use the following statistics to solve the problem.

n = 15     = $1831.067         S = $506.59