Question

A law enforcement agent believes that 80% of the drivers stopped on Saturday nights for speeding are under the influence of alcohol. Suspecting that the proportion under the influence may be higher than 80%, a SRS of 160 drivers who were stopped for speeding on a Saturday night was taken. 136 of the drivers in the sample were under the influence of alcohol.

A) What are the appropriate null and alternative hypotheses?

		H0: π = 0.80 versus Ha: π > 0.80
		H0: π = 0.85 versus Ha: π ≠ 0.85
		H0: π = 0.80 versus Ha: π ≠ 0.85
		H0: π = 0.80 versus Ha: π = 0.85

B) What is the value of the test statistic for this problem?

		z = 1.37
		z = 1.58
		z = 1.68
		z = 1.26
		z = 1.48

C)What is the p-value for this test?

		0.0694
		0.0571
		0.1329
		0.0727
		0.0853

D) What is the conclusion and WHY?

		Accept H0 (or fail to reject Ha), since p-value > 0.05
		Accept H0 (or fail to reject Ha), since p-value < 0.05
		Reject H0, since p-value > 0.05
		Reject H0, since p-value < 0.05

E) In real life language, we can summarize the results as follows:

		The proportion speeding under the influence is not 0.80.
		The proportion speeding under the influence is 0.80.
		There was enough evidence in the data to prove the proportion speeding under the influence is higher than 0.80.
		There was not enough evidence in the data to prove the proportion speeding under the influence is higher than 0.80.

Answer 1

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