STA 2023

Q9

A random sample of 79 eighth gradestudents' scores on a national mathematics assessment test has a mean score of 284. This test result prompts a state school administrator to declare that the mean score for thestate's eighth graders on this exam is more than 280. Assume that the population standard deviation is 39. At =0.15, is there enough evidence to support theadministrator's claim? Complete parts(a) through(e).

(a) Write the claim mathematically and identify H0 and Ha.

(b) Find the standardized test statisticz, and its corresponding area.

(c) Find theP-value.

(e) Interpret your decision in the context of the original claim.

Q10

A nutritionist claims that the mean tuna consumption by a person is 3.4 pounds per year. A sample of 50 people shows that the mean tuna consumption by a person is 3.3 pounds per year. Assume the population standard deviation is 1.02 pounds. At =0.05, can you reject theclaim?

(a) Write the claim mathematically and identify H0 and Ha.

(b) Find the standardized test statisticz, and its corresponding area.

(c) Find theP-value.

(e) Interpret your decision in the context of the original claim.

Q11

A company that makes cola drinks states that the mean caffeine content per12-ounce bottle of cola is 40 milligrams. You want to test this claim. During yourtests, you find that a random sample of thirty12-ounce bottles of cola has a mean caffeine content of 41.4 milligrams. Assume the population is normally distributed and the population standard deviation is 7.6 milligrams. At =0.02, can you reject thecompany's claim? Complete parts(a) through(e).

(a) Write the claim mathematically and identify H0 and Ha.

(b) Find the standardized test statisticz, and its corresponding area.

(c) Find theP-value.

(e) Interpret your decision in the context of the original claim.

Q12

A company claims that the mean monthly residential electricity consumption in a certain region is more than 860 kiloWatt-hours (kWh). You want to test this claim. You find that a random sample of 64 residential customers has a mean monthly consumption of 890 kWh. Assume the population standard deviation is 124 kWh. At =0.05, can you support theclaim? Complete parts(a) through(e).

(a) Write the claim mathematically and identify H0 and Ha.

(b) Find the standardized test statisticz, and its corresponding area.

(c) Find theP-value.

(e) Interpret your decision in the context of the original claim.