Question

A poll of 58 people reveals that 55.9% prefer Pepsi to Coca-Cola. You want to test the hypothesis that among the population Coca-Cola is preferred to Pepsi.

Report the z-statistic for this test.

Note: Respondents only have the choice of the two, so Coca-Cola is preferred to Pepsi if the proportion who prefer Pepsi is less than 50%.

Answer 1

solution

Test statistic = z

= - P0 / [P0 * (1 - P0 ) / n]

=0.559-0.50 / [(0.50*0.50) / 58]

Z= 0.90