Statistics Questions

Question

A publisher reports that 33% of their readers own a laptop. A marketing executive wants to test the claim that the percentage is actually different from the reported percentage. A random sample of 250 found that 28% of the readers owned a laptop. Find the value of the test statistic. Round your answer to two decimal places.

Answer 1

n=250

Population proportion=p= 0.33

Sample proportion= p hat = 0.28

Assumptions:

1. Simple random Sample.... checked
2. np>5 ? 250*.33= 82.5>5..... checked
3. n(1-p)>5 ? 250*.67 = 167.5 > 15 checked

then a normal distribution and

t stat. = ( p - phat)/ SD SD = sqrt(p(1-p))/n)= 0.0297

plugging in values t stat = (0.28-.33)/0.0297 = -1.68