Hypothesis Testing for the Mean: not known

Testing a Claim about a Mean: not KnownWe first need to make sure we meet the requirements.1. The sample observations are a simple random sample.2. The value of the population standard deviation is not known3. Either the Population is normal, or Test Statistic for Testing a Claim about a Proportion

Testing a Claim about a Mean: KnownP-value method in 5 Steps1. State the hypothesis and state the claim. 2. Compute the test value. (Involves find the sample statistic). 3. Draw a picture and find the P-value.4. Make the decision to reject or not. (compare P-value and 5. Summarize the results.

Testing a Claim about a Mean: KnownA simple random sample of 40 recorded speeds is obtained from cars traveling on a section of Highway 405 in Los Angeles. The sample has a mean of 68.4 mi/h and a standard deviation of 5.7 mi/h Use a 0.05 significance level to test the claim that the mean speed of all cars is greater than the posted speed limit of 65mi/h.1. 1. and

2. P-value 3. 0.000537 < 0.05 so we reject the null.4. There is sufficient evidence to support the claim that the

mean is greater than 65 mi/hr.Or use [Stat]Test

Testing a Claim about a Mean: Known• In an analysis investigation the usefulness of pennies, the

cents portions of 100 randomly selected credit card charges are recorded. The sample has a mean of 47.6 cents and a standard deviation of 33.5 cents. If the amounts from 0 cents to 99 cents are all equally likely, the mean is expected to 49.5 cents. Use a 0.01 significance level to test the claim that the sample is from a population with a mean equal to 49.5 cents. What does the result suggest about the cents portions of credit charge charges?

Testing a Claim about a Mean: Known• Homework!!

8-5: 13-27 odd