1) A coffee machine dispenses coffee into paper cups. Each cup is supposed to contain 8 ounces
of coffee, but the amount varies slightly from cup to cup. Here are the amounts measured in a
random sample of 12 cups. Is there evidence that the machine is shortchanging customers? Test
at the .01 significance level.
7.9 7.7 8.0 8.1 7.8 7.6 7.8 7.7 7.9 8.0 7.8 7.9
a. Hypotheses:
b. Mechanics, include a picture of your test with appropriate test statistics and the P-value.
c. Conclusion, in context:
d. Confidence interval in context. Does this confidence interval support your hypothesis test
conclusion? Explain.
Solution
A.H0 = machine is shortchanging the customers. B.mean = 7.93 sd = 2.8 P(z>2/3) =
0.38 c.Dont reject h0 d.CI = mean +/- sd*z/root n ==>(7.83.
1) A coffee machine dispenses coffee into paper cups. Each cup is su.pdf
1. 1) A coffee machine dispenses coffee into paper cups. Each cup is supposed to contain 8 ounces
of coffee, but the amount varies slightly from cup to cup. Here are the amounts measured in a
random sample of 12 cups. Is there evidence that the machine is shortchanging customers? Test
at the .01 significance level.
7.9 7.7 8.0 8.1 7.8 7.6 7.8 7.7 7.9 8.0 7.8 7.9
a. Hypotheses:
b. Mechanics, include a picture of your test with appropriate test statistics and the P-value.
c. Conclusion, in context:
d. Confidence interval in context. Does this confidence interval support your hypothesis test
conclusion? Explain.
Solution
A.H0 = machine is shortchanging the customers. B.mean = 7.93 sd = 2.8 P(z>2/3) =
0.38 c.Dont reject h0 d.CI = mean +/- sd*z/root n ==>(7.83
