Question

In a study of cellphone use and brain hemispheric dominance, an Internet survey was e-mailed to 5000 subjects randomly selected from an online group involved with ears. 717 surveys were returned. Use a 0.01 significance level to test the claim that the return rate is less than 15%.

Answer 1

Here we have to test

n = Total number of subjects selected randomly from an online group = 5000

x = Number of subjects were returned = 717

Here

and

So conditions are satisfied.

Test statistic:

Where

                         

                          = 0.00505               (Round to 5 decimal)

Z = -1.31       (Round to 2 decimal)

P value = P(Z < -1.31)

   = 0.0951    (From statistical table of z values)          

Level of significance = alpha = 0.01

Here P value = 0.0951 > alpha = 0.01

So we do not reject H0.

Conclusion: There is insufficient evidence to conclude that the return rate is less than 15%