The city fuel economy of a 2009 Toyota 4Runner 2WD 6 cylinder 4 L automatic 5-sp

Question

The city fuel economy of a 2009 Toyota 4Runner 2WD 6 cylinder 4 L automatic 5-speed using regular gas is a normally distributed random variable with a range 28 MPG to 37 MPG. (a) Estimate the standard deviation using Method 3 (the Empirical Rule for a normal distribution). (Round your answer to 4 decimal places.) Standard deviation (b) What sample size is needed to estimate the mean with 90 percent confidence and an error of ± 0.25 MPG? (Enter your answer as a whole number (no decimals). Use a z-value taken to 3 decimal places in your calculations.) Sample size

Explanation / Answer

a)

SD = (b - a) / 6 = (37-28) / 6 = 1.5000

b)

z value = 1.645

Sample size = ( z s / e)2

sample size = ( 1.645*1.5 / 0.25)2 = 97.4169 = 98

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.