Suppose that the average number of miles that a car is driven in the first three years is 41,500. To determine whether leased cars are driven more than "average", 25 leased cars were sampled and the average number of miles on the leased cars was 43,780 with a standard deviation of 10,520. To determine whether the average number of miles on leased cars is statistically significantly greater than the number of miles on other cars (using the 5% level of significance), what is the critical value?

Because of different sales ability, experience, and devotion, the incomes of real estate agents vary considerably. Suppose that in a large city the annual income is normally distributed with a standard deviation of $15,000. A real estate industry expert claims that the mean annual income of all real estate agent in the city is equal to $79000. A sample of 30 real estate showed that their mean annual income was $84230. Test the manager's claim using a level of significance of 0.05. what is your conclusion

Consider a small scale example, comparing how temperatures have changed in the US from 1968 to 2008. The daily high temperature reading on January 1 was collected in 1968 and 2008 for 51 randomly selected locations in the continental US. The locations are the same for both years. The difference between the two readings (temperature in 2008 - temperature in 1968) was calculated for each of the 51 different locations. The average of these 51 values was 1.24 degrees with a standard deviation of 4.25 degrees. We are interested in determining whether this provides strong evidence of temperature warming in the continental US. (Does the data provide evidence that the true mean temperature is greater in 2008 than in 1968?) Justify by using a confidence interval or a hypothesis test with α = 0.05. What type of error are you in danger of making?

b. In a class of twenty-five 15-year old girls the average height is M = 62.60 inches. The national average for girls at this age is reported as follows: µ = 63.80 inches with a standard deviation, s = 2.66 inches.     Compute z score

According to Kaiser Family Foundation survey in 2011 and 2010, the average premium for employer-sponsored health insurance for family coverage was $15,073 in 2011 and $13,770 in 2010 (USA TODAY, September 29, 2011). Suppose that these averages were based on random samples of 250 and 200 employees who had such employer-sponsored health insurance plans for 2011 and 2010, respectively. Further assume that the population standard deviations for 2011 and 2010 were $2160 and $1990, respectively.

The average credit card debt for a recent year was $8,776. Five years earlier the average credit card debt was $8,189. Assume sample sizes of 32 were used and the population standard deviations of both samples were $690. Is there evidence to conclude that the average credit card debt has increased?

Suppose that in 2020 the average song length is 245 seconds, with a standard deviation of 28 seconds. what is the approximate standard error for the sampling distribution of mean song lengths due samples size of 64 A. 28.0 B. 2.3 C. 7.0 d. 3.5

A study is done to determine if students in the California state university (CSU) system take longer to graduate, on average, than students enrolled in private universities using the significant level of 5%. One hundred students from both the California state university system and private universities are surveyed. Suppose that from years of research, it is known that the population standard deviations are 1.5811 years for CSU and 1 year for private universities. The following data are collected. The California state university system students took on average 4.5 years with a standard deviation of 0.8. The private university students took on average 4.1 years with a standard deviation of 0.3. What is the decision rule of rejecting the null hypothesis

In one city, the average amount of time that tenth-graders spend watching television each week is 23 hours. The principal of Birchwood High School believes it is less for the 10th grade students that at his school.  For a sample of 95 tenth-graders from the school, the mean amount of time spent watching television per week was 21.9 hours.  Assuming a population standard deviation of 3.1 hours, does the data provide sufficient evidence to conclude that for all tenth-graders at Birchwood High school, the mean amount of time spent watching television per week is less than the city average of 23 hours?  Perform the appropriate hypothesis test using a significance level of 0.005.  What are the hypotheses?         What is the test statistic? Is it a z or a t?         Find the P-value for this test statistic. How does it compare to the significance level?  On the normal curve, indicate the location of the test statistic  and  the p-value. (label them on the graph)                 Write…