Question

Reginald Brown, an inspector from the Department of Weights and Measures, weighed 15 eighteen-ounce cereal boxes of corn flakes. He found their mean weight to be 17.8 ounces with a standard deviation of 0.4 ounces. Are the cereal boxes lighter than they should be?

Using significance level of 0.01, perform a hypothesis test.

Step #1: State the hypotheses and identify the claim.

Step #2: What is the test value?

Step #3: What kind of test is being run?

Step #4: What is the p-value?

step5: Reject or not to reject the null hypothesis

#5: Conclusion statement.

There is not enough evidence to support the claim that the average cereal box weighs less than 18 ounces or

There is enough evidence to support the claim that the average cereal box weighs less than 18 ounces

Answer 1

Step 1) Ho : 18

H1 : 18 ( claim)

Step2) test statistic t

t = (xbar - )/(s/√n)

t = ( 17.8 - 18)/(0.4/√15)

t test statistic = -1.94

Step3) test : t test

Step 4) p-value for t = -1.94 and d.f = n -1 = 14

Using t table

p-value = P( t < -1.94) d.f = 14

p-value = 0.0364

Step 5) here p-value = 0.0364 > 0.01

Decision : Not to reject the null hypothesis

Step 6) conclusion : There is not enough evidence to support the claim that the average cereal box weighs less than 18 ounces