Question

Experts believe the rate of obesity (defined as having a BMI greater than 30) of adults in the United States is approximately 24.5%. A Gallup poll examined the rate of obesity in adults in the United States with a survey of 86,664 randomly sampled U.S. adults. Of the adults surveyed, 23,053 said that they were obese. The shape of the sampling distribution for the sample proportion when taking samples of size 86,664 from this population follows a ____________ distribution.

Answer 1

Normal distribution.

Explanation:

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean
`\mu` and standard deviation
`\sigma`, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean
`\mu` and standard deviation
`s = (\sigma)/(√(n))`.

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean
`\mu = p` and standard deviation
`s = \sqrt{(p(1-p))/(n)}`

In this question:

Samples larger than 30, which means that the sampling distribution for the sample proportion follows a normal distribution.