Unit 6: Inference for Proportions
Statistics · Unit 6 · Paper 1

Inference for Proportions unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1Paper 2Paper 3
Each paper is built from this unit’s 20 terms and is the same for everyone, so a teacher can assign “Unit 6, Paper 1” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.
Suggested time 36 min 33 points0/17 attempted
1

Why we never accept the null

2

Choosing sample size for a margin of error

3

Confidence interval structure

4

Null and alternative hypotheses

5

A p-value is not the probability the null is true

6

The four-step template

7

Conclusion wording

8

Conditions for a one-proportion z-interval

9

One-sided vs two-sided alternatives

10

Interpreting a confidence interval

11

Using a confidence interval to test

12

Two-proportion z-test pooling

Short answer 1. Define or explain: Type I and Type II errors

3 pts

Short answer 2. Define or explain: p-value definition

3 pts

Short answer 3. Define or explain: Interpreting a confidence level

3 pts

Short answer 4. Define or explain: Power

3 pts

Free response

9 pts

A coffee chain claims that 60% of its customers prefer its new house blend. A skeptical manager suspects the true proportion is lower. In a random sample of 150 customers, 78 prefer the new blend. Use α = 0.05.

State the hypotheses, defining the parameter in context.

Verify the conditions for a one-proportion z-test.

Calculate the test statistic and the P-value.

State a conclusion in the context of the problem.

Describe a Type I error in this context and its consequence for the chain.