Which of the following situations involves testing a claim about a single population proportion?

• A. A company tests whether the average time to assemble a product is less than $30$ minutes.
• B. A scientist compares the mean heights of plants grown with two different fertilizers.
• C. A study examines if the variances of test scores from two different schools are equal.
• D. A researcher wants to determine if the proportion of students at a university who own a laptop is greater than $0.80$.

Answer: (D)

Verified step by step guidance

1. Identify the key characteristic of the problem: testing a claim about a single population proportion involves making an inference about the proportion (or percentage) of individuals in one population that have a certain attribute.
2. Review each option to see if it involves a proportion from a single population:
3. - The first option tests an average time, which relates to a population mean, not a proportion.
4. - The second option compares mean heights between two groups, which involves two population means, not a single proportion.
5. - The third option compares variances between two groups, which involves two population variances, not a proportion.
6. - The fourth option tests whether the proportion of students owning a laptop is greater than 0.80, which is a claim about a single population proportion.