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5) A car salesman claims that a particular make of car would give a mean mileage

ID: 3440835 • Letter: 5

Question

5) A car salesman claims that a particular make of car would give a mean mileage of greater than 20 miles/gallon. To test the claim, a field experiment was conducted where 10 cars were each run on one gallon of gas. The results (in miles) were: 23, 18, 22, 19, 19, 22, 18, 18, 24, 22. The sample standard deviation (s) = 2.32. What formula would you use to test whether the sample results support the salesman's claim? Use  a = .05.

x - t(s ÷ n)   <   µ   <  x + t(s ÷ n)

µ = x ÷ N

z =  (x - x-bar) ÷  /n

t =  (x - x-bar) ÷ s/n

WHY?

A)

x - t(s ÷ n)   <   µ   <  x + t(s ÷ n)

B)

µ = x ÷ N

C)

z =  (x - x-bar) ÷  /n

D)

t =  (x - x-bar) ÷ s/n

Explanation / Answer

Option (D) is the correct formula, there is no reason, its just fact.

(A) is for CI, B is for sample mean, (c) is used when population std dev is known.

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