Question

Marketers want to know about the differences between men's and women's use of the Internet. A research poll in April 2009 from a random sample of adults found that 2358 of 3026 men use the Internet, while 2378 of 3169 women did.

a). Find the proportions of men and women who said they use the Internet at least occasionally.

b). What is the difference in proportions?

c) What is the standard error of the​ difference?

​d) Find a​ 95% confidence interval for the difference between percentages of usage by men and women nationwide.

C). What is the standard error of the difference?

d). Find a 95% confidence interval for the difference between percentages of usage by men and women nationwide.

Answer 1

a) The proportion of men who said they use the Internet at least occasionally is ,

p1=X1/n1=2358/3026=0.7792

The proportion of women who said they use the Internet at least occasionally is ,

p1=X1/n1=2378/3169=0.7504

b) The difference on proportion = p1-p2=0.7792-0.7504=0.0288

c) The pooled estimate is ,

Q=1-P=0.2355

Therefore , the standard error of the difference is ,

d) The 95% confidence interval for the difference between percentages of usage by men and women nationwide

; Since , ; From the standard normal probability table