Question

Problem

In 2012, at the beginning of California's most recent drought, 14% of front yards in Los Angeles County were drought tolerant. Note: A "drought-tolerant" front yard is a yard consisting of artificial turf, rocks, or water-efficient plants. A hydrologist believes that, due to landscaping rebate programs, the population proportion of drought-tolerant front yards in Los Angeles County has increased since 2012.

The hydrologist observes a random sample of 800 front yards from across Los Angeles County and finds that 140 out of the 800 front yards are drought tolerant.

Is there sufficient evidence to conclude that the population proportion of drought-tolerant front yards in Los Angeles County has increased since 2012? Use an α = 0.01 level of significance.

Question 1

State the null and alternative hypotheses (using symbols).

Question 2

Explain what it would mean for the hydrologist's study to make a Type I Error.

Question 3 (Optional)

Verify the requirements for this hypothesis test. Briefly show that each requirement is satisfied.

Question 4

Test the hypothesis using either the classical (test statistic) approach or the P-value approach. Show all steps to your approach. Then state whether you reject H 0 or do not reject H 0.

Question 5

Is there sufficient evidence to conclude that the population proportion of drought-tolerant front yards in Los Angeles County has increased since 2012? State your conclusion in one or two sentences.

Answer 1

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