# Question: The fuel economy of a 2011 Lexus RX 350 2WD

The fuel economy of a 2011 Lexus RX 350 2WD 6 cylinder 3.5 L automatic 5-speed using premium fuel is normally distributed with a known standard deviation of 1.25 MPG. If a random sample of 10 tanks of gas yields a mean of 21.0 MPG, find the 95 percent confidence interval for the true mean MPG.

**View Solution:**## Answer to relevant Questions

Guest ages at a Vail Resorts ski mountain typically have a right-skewed distribution. Assume the standard deviation (σ) of age is 14.5 years. (a) Even though the population distribution of age is - right-skewed, what will ...For each value of d.f. look up the value of Student's t in Appendix D for the stated level of confidence. How close is the t-value to the corresponding z-value (at the bottom of the column for d.f. = ∞) ? a. d.f. = 40, 95 ...Prof. Green gave three exams last semester. Scores were normally distributed on each exam. Below are scores for 10 randomly chosen students on each exam. (a) Find the 95 percent confidence interval for the mean score on each ...Of 43 bank customers depositing a check, 18 received some cash back. (a) Construct a 90 percent confidence interval for the proportion of all depositors who ask for cash back. (b) Check the normality assumption of p. For each level of precision, find the required sample size to estimate the mean starting salary for a new CPA with 95 percent confidence, assuming a population standard deviation of $7,500 (same as last year). a. E = ...Post your question