Records on a Fleet of Trucks Reveal That the Average

question 50

Essay

Records on a fleet of trucks reveal that the average life of a set of spark plugs is normally distributed with a mean of 22,100 miles. The fleet owner purchased 18 sets and found that the sample average life was 23,400 miles; the sample standard deviation was 1,412 miles. To decide if the sample data support the company records that the spark plugs average 22,100 miles, state your decision in terms of the null hypothesis. Use a 0.05 level of significance.

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Definitions:

Treasury Bill

A short-term government security issued at a discount from the par value and pays no interest, maturing in a year or less.

Treasury Bond

Long-term government debt securities with a fixed interest rate and maturity of more than 10 years.

Short-Term

A period of time that is relatively brief, usually focusing on immediate or near-future events or goals, often contrasted with long-term perspectives.

Student Loans

Borrowed money that is used to pay for educational expenses and is expected to be paid back with interest.