improper driving. in 2009, 45.6% of motor vehicle accidents involved no improper
ID: 3134698 • Letter: I
Question
improper driving. in 2009, 45.6% of motor vehicle accidents involved no improper driving. in an area comprised of six adjoining counties, it was found that out of 110 randomly selected accidents, 60 involved improper driving in some way. at the 0.10 level of significance, is there sufficient evidence to conclude that the proportion of accidents involving improper driving differs from the 2009 proportion?
a. state the hypotheses and identify the claim
b. find the critical value(s)
c. compute the test value
d. make the decision
e. summarize the results
Explanation / Answer
A)
Formulating the null and alternatuve hypotheses,
Ho: p = 0.456
Ha: p =/= 0.456 (claim)
[ANSWERS, HYPOTHESES]
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b)
As alpha = 0.10 two tailed, then the critical z values are
z = -1.645, 1.645 [ANSWER]
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c)
As we see, the hypothesized po = 0.456
Getting the point estimate of p, p^,
p^ = x / n = 0.545454545
Getting the standard error of p^, sp,
sp = sqrt[po (1 - po)/n] = 0.04748818
Getting the z statistic,
z = (p^ - po)/sp = 1.883722324 [ANSWER]
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d)
As |z| > 1.645, we reject Ho.
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e)
There is significant evidence that the proportion of accidents involving improper driving differs from the 2009 proportion at 0.10 level. [CONCLUSION]
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