Question

Supermarkets throughout the United States sell an average of 460 quarts of milk/day with a standard deviation of 20 quarts. Over a sample of 36 days chosen at random a supermarket sells an average of 470 quarts/day. At the 0.05 level of significance, does the store sell more milk than the national average? a) what is the research problem? (b) state null and alternative hypothesis (c) It this one or two tailed test? why? (d) what is the critical value? (e) What is the decision rule? (f) calculate the statistic (g) what is your decision regarding null hypothesis and why? (h) interpretation of the results

Answer 1

= 460, = 20, n = 36, = 470, = 0.05

a) It is one tailed z test . The research problem is we want to test whether store     sell more milk than the national average

b) Ho: = 460

Ha: > 460

c) It is One tailed test.

d) Critical value for = 0.05 with one tailed test is

  Critical value = 1.645

e) Decision Rule:

Reject Ho if ( test statistics ) > ( Critical value )

f) Calculate test statistics

test statistics (z) = 3

g) Since (test statistics = 3) > (Critical value= 1.645)

Hence, Null hypothesis (Ho) is rejected.

h) Therefore, there is enough evidence to claim that the store sell more milk than national average at the 0.05 significance level.