Question

A marketing research firm believes that more than half of adults drink mostly either regular or diet soda. To test this claim, Gallup took a nationally representative sample of 2027 adults and asked them about their soda consumption. The survey shows that 950 of those surveyed drink mostly either regular or diet soda. The test statistics for the above hypthesis test for the proportion of adults who drink mostly either regular or diet soda is:________. (Round your answer to two decimal places)

Answer 1

The test statistic is z = -2.82.

Explanation:

A marketing research firm believes that more than half of adults drink mostly either regular or diet soda.

This means that the null hypothesis is:
`H_(0) = 0.5`

The alternate hypothesis is:
`H_(a) > 0.5`

The test statistic is:

`z = (X - \mu)/((\sigma)/(√(n)))`

In which X is the sample mean,
`\mu` is the value tested at the null hypothesis,
`\sigma` is the standard deviation and n is the size of the sample.

0.5 tested at the null hypothesis:

This means that:

`\mu = 0.5, \sigma = √(0.5*0.5) = 0.5`

Gallup took a nationally representative sample of 2027 adults and asked them about their soda consumption. The survey shows that 950 of those surveyed drink mostly either regular or diet soda.

This means that
`n = 2027, X = (950)/(2027) = 0.4687`

Test statistic:

`z = (X - \mu)/((\sigma)/(√(n)))`

`z = (0.4687 - 0.5)/((0.5)/(√(2027)))`

`z = -2.82`

The test statistic is z = -2.82.