In a recent survey, 10 percent of the participants rated Pepsi as being "concerned with my health." PepsiCo's response included a new "Smart Spot" symbol on its products that meet certain nutrition criteria, to help consumers who seek more healthful eating options. Suppose a follow-up survey shows that 29 of 200 persons now rate Pepsi as being "concerned with my health." What is the p-value for the test that would show whether or not there is sufficient evidence that the percentage has increased?

Respuesta :

Answer:

[tex]z=\frac{0.145 -0.1}{\sqrt{\frac{0.1(1-0.1)}{200}}}=2.121[/tex]  

[tex]p_v =P(z>2.121)=0.0170[/tex]  

Step-by-step explanation:

Data given and notation

n=200 represent the random sample taken

X=29 represent the persons who now rate Pepsi as being "concerned with my health

[tex]\hat p=\frac{29}{200}=0.145[/tex] estimated proportion of persons who now rate Pepsi as being "concerned with my health

[tex]p_o=0.10[/tex] is the value that we want to test

[tex]\alpha[/tex] represent the significance level

z would represent the statistic (variable of interest)

[tex]p_v[/tex] represent the p value (variable of interest)  

Concepts and formulas to use  

We need to conduct a hypothesis in order to test the claim that true percentage is higher than 10% or 0.1.:  

Null hypothesis:[tex]p\leq 0.1[/tex]  

Alternative hypothesis:[tex]p > 0.1[/tex]  

When we conduct a proportion test we need to use the z statistic, and the is given by:  

[tex]z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}}[/tex] (1)  

The One-Sample Proportion Test is used to assess whether a population proportion [tex]\hat p[/tex] is significantly different from a hypothesized value [tex]p_o[/tex].

Calculate the statistic  

Since we have all the info requires we can replace in formula (1) like this:  

[tex]z=\frac{0.145 -0.1}{\sqrt{\frac{0.1(1-0.1)}{200}}}=2.121[/tex]  

Statistical decision  

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.  

The next step would be calculate the p value for this test.  

Since is a right tailed test the p value would be:  

[tex]p_v =P(z>2.121)=0.0170[/tex]