Gasoline pumped from a supplier’s pipeline is supposed to have an octane rating of 87.5. For 13 consecutive days, a liter of gas from the pipeline was obtained and analyzed. The resulting octane readings for these 13 days are given below:88.6     86.4     87.2     88.4     87.2     87.6     86.8     86.1     87.4     87.3     86.4     86.6     87.1Here is the data set in StatCrunch. The supplier wants to test the claim that the octane reading from the pipeline has a true mean that is less than 87.5 at the 5% level of significance.Are the results of the test statistically significant?

Gasoline pumped from a supplier’s pipeline is supposed to have an octane rating of 87.5. For 13 consecutive days, a liter of gas from the pipeline was obtained and analyzed. The resulting octane readings for these 13 days are given below:88.6     86.4     87.2     88.4     87.2     87.6     86.8     86.1     87.4     87.3     86.4     86.6     87.1Here is the data set in StatCrunch. The supplier wants to test the claim that the octane reading from the pipeline has a true mean that is less than 87.5 at the 5% level of significance.What is the decision rule (do you reject the null and conclude the alternative or do you fail to reject the null)? Be sure to state why.

An ABC News poll in April 2007 of a random sample of 1002 adults nationwide asked about various measures the government could take to try to reduce future global warming (www.pollingreport.com/enviro.htm). When asked whether the government should increase taxes on gasoline so people either drive less or buy cars that use less gas, 681 people said no. Test, at the 0.01 level of significance, the claim that the majority (more than 50%) of U.S. adults believe that the government should not increase taxes on gasoline to help reduce future global warming.State the value of the test statistic. Round to two decimal places.

Experiments on animal learning often measure how long a mouse takes to get through a maze. For one particular maze, the true mean time is 18 seconds. A researcher thinks that a loud noise will help the mice to complete the maze faster. She measures the average time, x-bar, required for 10 mice to complete the maze when the loud noise is played. Which is a suitable null hypothesis in this situation?

The New York Department of Health conducted an investigation on the effect of a new vitamin supplement given to pregnant women. The results in the following table show the mean, standard deviation, and standard error of the birth weights (in kilograms) of a random sample of 16 male babies whose mothers took the vitamin supplement when pregnant. n mean std. deviation std. error Weight 16 3.675 0.657 0.164 Interpret the confidence interval in the terms of the problem.

Public Policy Polling (PPP), a reputable polling company, asked the following question in a previous Halloween-eccentric public opinion poll:“If zombies took over the world and human civilization collapsed, how long do you think you could survive: less than one week, less than one month, less than six months, less than one year, or more than a year?” Of the 1,200 likely voters who were asked this question, 324 said “Less than one week”.Do we know the true population percentage of likely voters who said that they would survive a zombie apocalypse for less than one week?

According to the Insurance Information Institute, the mean expenditure for auto insurance in the United States was $774 in 2002. An insurance sales person believes that the mean expenditure for auto insurance is different now. He obtains a random sample of 35 auto insurance policies and determines the mean expenditure to be $815 with a standard deviation of $88.31. Is there sufficient evidence to conclude that the mean expenditure for auto insurance is different from the 2002 amount at the α = 0.10 level of significance? State the null and alternative hypothesis for this situation, and the type of tail.

It is believed that applying zinc to soil can affect the amount of herbage (leaves and stems) of plants grown. In an experiment, the regression line for predicting the amount of herbage (y) from the amount of zinc applied (x) is y-hat = 3.29 – 3.825x.  Which of the following can you conclude from this regression line?

An ABC News poll in April 2007 of a random sample of 1002 adults nationwide asked about various measures the government could take to try to reduce future global warming (www.pollingreport.com/enviro.htm). When asked whether the government should increase taxes on gasoline so people either drive less or buy cars that use less gas, 681 people said no. Test, at the 0.01 level of significance, the claim that the majority (more than 50%) of U.S. adults believe that the government should not increase taxes on gasoline to help reduce future global warming.State the null and alternative hypothesis for this situation, and the type of tail.

Inferential statistics is so named because it allows us to examine a sample and make inferences about . . .