In a study of cell phone usage and brain hemispheric dominance, an Internet survey was e-mailed to 6967 subjects randomly selected from an online group involved with ears. There were 1331 surveys returned. Use a 0.01 significance level to test the claim that the return rate is less than 20%. Use the P-value method and use the normal distribution as an approximation to the binomial distribution.

Now we can find the p value using the alternative hypothesis and with the following probability:

We see that the p value is higher than the significance level of 0.01 so then we FAIL to reject the null hypothesis and there is NOT enough evidence to conclude that the return rate is less than 20% at 1% of significance

Step-by-step explanation:

Information given

n=6967 represent the random sample selected

X=1331 represent the surveys returned

estimated proportion of return rate

tex]p_o=0.2[/tex] is the value to verify

represent the significance level

z would represent the statistic

represent the p value

System of hypothesis

We test the claim that the return rate is less than 20%, then the system of hypothesis are:  

Null hypothesis:  

Alternative hypothesis:  

The statistic is given by:

(1)  

Replacing the info given we got:

Now we can find the p value using the alternative hypothesis and with the following probability:

We see that the p value is higher than the significance level of 0.01 so then we FAIL to reject the null hypothesis and there is NOT enough evidence to conclude that the return rate is less than 20% at 1% of significance

walter needs to make at least 5 more cookies but no more than 40. 5 ≥ x ≥ 40;

step-by-step explanation:

walter has to make a minimum of 20 cookies. he already has 15 cookies made, so he must make 5 more to meet the minimum.

the maximum amount of cookies he can make is 55. he already has 15, so he has to make no more than 40 more cookies to meet the maximum.

point a is the center of the circle that passes through points e, f, and g and the center of the circle that passes through points x, y, and z.