Question

In a recent survey, 10 percent of the participants rated Pepsi as being "concerned with my health." PepsiCo's response included a new "Smart Spot" symbol on its products that meet certain nutrition criteria, to help consumers who seek more healthful eating options.

Suppose a follow-up survey showing that 49 of 400 persons now rate Pepsi as being "concerned with my health", calculate the z statistic. (Round your answer to 3 decimal places.)

Answer 1

z statistic equals 1.5

Explanation:

z-score can be calculated using the formula

`z=\frac{p(s)-p}\sqrt{(p(1-p))/(N)}` where

• p(s) is the proportion of follow-up survey (
  `(49)/(400)`)
• p is the base proportion (0.10)
• N is the sample size of follow-up survey (400)

putting these numbers in the formula we get:

`z=\frac{0.1225-0.1}\sqrt{(0.1*0.9)/(400)}` = 1.5