2) A humane society claims that 30% of U.S. households own a cat. In a random sample of 210 U.S. households, 80 say they own a cat. Is there enough evidence to show this percent has changed? Use a level of significance of 0.05.

Respuesta :

ANSWER:

There is enough evidence to reject the humane society claims

STEP-BY-STEP EXPLANATION:

Given:

p = 0.3

q = 1 - p = 1 - 0.3 = 0.7

n = 210

x = 80

Therefore:

[tex]\hat{p}=\frac{x}{n}=\frac{80}{210}=0.381[/tex]

The critical values are:

[tex]Z_0=\pm1.96\text{ due }\alpha=0.05[/tex]

The test statistic is:

[tex]\begin{gathered} Z=\frac{\hat{p}-p}{\sqrt[]{\frac{pq}{n}}} \\ \text{ replacing:} \\ Z=\frac{0.381-0.3}{\sqrt{\frac{0.3\cdot0.7}{210}}} \\ Z=2.56 \end{gathered}[/tex]

Observe that

Z < 1.96

Therefore, reject the null hypothesis

There is enough evidence to reject the humane society claims