Chapter 10 Review

A T-test sample has 7 pairs of samples. The distribution should contain ____________

• 16 degrees of freedom

• 15 degrees of freedom

• 5 degrees of freedom

• 6 degrees of freedom

Define a Type I error?

• The failure to reject a false null hypothesis
• Rejecting a true null hypothesis
• The acceptance to reject a null hypothesis
• Accepting a true null  hypothesis

When do you use a t-value instead of a z-value?

• When n < 30

• When n ≥ 30

• When all of the planets align

• When the teacher says so

Which of the following is the FIRST step of a hypothesis test?

• Check assumptions & conditions
• Find your test statistic
• State your conclusion
• State your null & alternative hypotheses

A test is made of H₀ : µ₁ = µ₂ versus H₁ : µ₁ ≠ µ₂ is performed using α = 0.01 significance level. The value of the test statistic is z = -2.68 and it is concluded that H₀ is rejected.

If the true value of µ is 17, is the conclusion a Type I Error, Type II error, or a correct decision?

• Type I

• Type II

• Correct Decision

What is the critical value (in a test about proportions) for a left-tailed test with α = 0.05 and n ≥ 30. 

• z₀ = -1.645
• z₀ = -2.33
• z₀ = -1.96
• z₀ = 2.58

State the null and alternative hypotheses.

The mean cell phone bill for females (1) is higher than the mean cell phone for males (2).

• H_0: μ₁ > μ₂ H_a: μ₁ ≤ μ₂

• H₀: μ₁ < μ₂ H_a: μ₁ ≥ μ₂

• H₀: μ₁ ≤ μ₂ H_a: μ₁ > μ₂

• H₀: μ₁ ≥ μ₂ H_a: μ₁ < μ_2

A Keebler sales rep claims that there are more chocolate chips in their cookie than in Chips Ahoy cookies.  You take a random sample of 20 Keebler cookies and find an average of 15.8 chips per cookie and a s= 3.7 chips. A random sample of 25 Chips Ahoy yields 14.2
chips per cookie and s=4.3 chips.
What is the conclusion of the test?

• There is enough evidence to reject the claim that there are more chips in Keeblers
• There is not enough evidence to reject the claim that there are more chips in Keeblers
• There is enough evidence to support the claim that there are more chips in Keeblers
• There is not enough evidence to support the claim that there are more chips in Keeblers

A market researcher suspects that employees at Company A were older on average than employees at company B. They obtained a random sample of employees ages from each company. Results are shown. Which is the correct calculation for the t-statistic?

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