Jessica Salas, President of Salas Products, is reviewing the warranty policy for her company's new model of automobile batteries. Life tests performed on a sample of 100 batteries indicated: (1) an average life of 75 months, (2) a standard deviation of 5 months, and (3) a bell-shaped battery life distribution. What percentage of the batteries will fail within the first 65 months of use?

A quiz related to digital knowledge was conducted. The quiz had 10 questions and covered topics such as the purpose of browser cookies, phishing scams, and privacy policies. The survey was given to 50 people. The mean score is 4.1 with a standard deviation of 2.6. We want to know if the data provide evidence that the mean score in the population is lower than 5. We will use alpha = 0.05 to make our decision. part a. Is this a one-sided or two-sided test? part b. What is the standard error for this problem? part c. How many degrees of freedom do we have for this problem? part d. What is the test statistic, t, for this problem? Based on your test statistic and degrees of freedom, the p-value will be between what two values? (If you cannot find the exact df in the table, round down to be safe. So if you have 38 df, round down to 30df.) Group of answer choices The p-value is between .1 and .05 The p-value is between .05 and .025 The p-value is between .025 and .01 The p-value…

A report about how American college students manage their finances includes data from a survey of college students. Each person in a representative sample of 793 college students was asked if they had one or more credit cards and if so, whether they paid their balance in full each month. There were 500 who paid in full each month. For this sample of 500 students, the sample mean credit card balance was reported to be $825. The sample standard deviation of the credit card balances for these 500 students was not reported, but for purposes of this exercise, suppose that it was $205. Is there convincing evidence that college students who pay their credit card balance in full each month have a mean balance that is lower than $907, the value reported for all college students with credit cards? Carry out a hypothesis test using a significance level of 0.01.   State the appropriate null and alternative hypotheses. H0: ? = 907 Ha: ? < 907 H0: ? = 907 Ha: ? > 907      H0: ? < 907…

The playing life of a Sunshine radio has a Normal distribution with a mean of 600 hours and a standard deviation of 100 hours.   What time frame would be considered unusual? What rule did you use to decide this?

Federal officials have investigated the problems associated with disposal of hazardous wastes. One disposal site is the abandoned Stringfellow acid pits in Riverside County, Calif. The EPA sampled water from 12 wells in nearby Glen Avon. The EPA standard for maximum allowable radiation level of drinking water is 13.35 pCi/L. Suppose that the sample of 12 water specimens resulted in a sample mean radiation level of 18.97 pCi/L and a sample standard deviation 6.12. Is this sufficient evidence to indicate that the water in Glen Avon has a mean radiation level that exceeds the EPA standard?. Use t test. (a = 0.05) Ho = 13.35 versus Η μ > 13.35 Let μ denote the true mean radiation level for well water in Glen Avon O Reject Null Hypothesis O Failed to Reject Null Hypothesis

The combined SAT scores for the students at a local high school are normally distributed with a mean of 1469 and a standard deviation of 296. The local college includes a minimum score of 1824 in its admission requirements. What percentage of students from this school earn scores that satisfy the admission requirement?

According to Current Population Reports, the population distribution of number of years of education for self-employed individuals in the United States has a mean of 13.6 and a standard deviation of 3.0.  Find the mean and standard error of the sampling distribution of ȳ for a random sample of  9 residents.