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a random sample of 20 purchases showed the amounts in the table (in $). 43.66 66.43...

a random sample of 20 purchases showed the amounts in the table (in $). 43.66 66.43 35.80

The mean is $51.47 and the standard deviation is $16.76 47.29 70.09 36.08

a) construct a 95% confidence level interval for the mean purchases of   27.34 51.08 36.49

all the customers, assuming that the assumptions and condition for the 47.67 71.47 88.39

confidence level have been met. 66.53 53.97 39.31

b) How large is the margin of error? 50.50 74.53 39.43

c) how would the confidence level change if you had assumed that the standard 28.00 55.28   

deviation was known to be $17.   

Math   Statistics-And-Probability   
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