License records in a county reveal that 15 of cars are subco

License records in a county reveal that 15% of cars are subcompacts, 25% compacts, 40% midsize, and the             rest are an assortment of other styles and models. A random sample of accidents involving cars licensed in the county was drawn and is summarized below:

Subcompact

36

Compacts

58

Midsize

74

Other

29

Total:

197

What is the expected number of accidents in the compacts category?

Can we infer that certain sizes of cars are involved in a higher than expected number of accidents? Please provide your answers in the below answer sheet:       

            Significant? _________________ (Yes or No)

            Test Statistic: ________________ (3 decimals)

            p-value: ________________ (3 decimals)

Solution

License records in a county reveal that 15% of cars are subcompacts, 25% compacts, 40% midsize, and the             rest are an assortment of other styles and models. A random sample of accidents involving cars licensed in the county was drawn and is summarized below:

What is the expected number of accidents in the compacts category? = 197*25/100 = 49.25

Goodness of Fit Test

observed

expected

O - E

(O - E)