Question

A​ case-control (or​ retrospective) study was conducted to investigate a relationship between the colors of helmets worn by motorcycle drivers and whether they are injured or killed in a crash. Results are given in the accompanying table. Using a

0.050.05

significance​ level, test the claim that injuries are independent of helmet color.

		Color of Helmet
		Black	White	Yellow	Red	Blue
Controls​ (not injured)		484484	344344	2626	165165	105105
Cases​ (injured or​ killed)		201201	9797	77	6969	5151

Click here to view the chi-square distribution table.

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Identify the null and alternative hypotheses. Choose the correct answer below.

A.

Upper H 0H0​:

Whether a crash occurs and helmet color are independent

Upper H 1H1​:

Whether a crash occurs and helmet color are dependent

B.

Upper H 0H0​:

Injuries and helmet color are dependent

Upper H 1H1​:

Injuries and helmet color are independent

C.

Upper H 0H0​:

Injuries and helmet color are independent

Upper H 1H1​:

Injuries and helmet color are dependent

D.

Upper H 0H0​:

Whether a crash occurs and helmet color are dependent

Upper H 1H1​:

Whether a crash occurs and helmet color are independent

2. what is the test statistic?

3. what is the critical value x squared?

4. fail to reject? or reject? why?

Answer 1