Prelim -Statistics

A manufacturer claims that his tires last at least 40,000 miles. A test on 25 tires reveals that the mean life of a tire is 39,750 miles, with a standard deviation of 387 miles. Test the Manufacturer’s claim at α = .01.

• Reject Ho

• Fail to reject Ho

• Reject Ha

• Fail to reject Ha

Which of the following shows a right-tailed test?

Answer choices

• H₀: µ > 15

• H₀: µ < 15

• Ha: µ > 15

• Ha: µ < 15

Find the critical value given the sample size and level of significance. Two-tailed, n=14,  α = 0.01

• 
  t*=-2.345 and t*=2.345

• 
  t*=-3.012 and t*=3.012

• t*=-1.645 and t*=1.645

• t*=3.012

A citrus grower's association believes that the mean consumption of fresh citrus fruits by families in the Philippines is at least 98 pounds per year. A random sample of 13 families in the Philippines has a mean consumption of 89.5 pounds per year with a standard deviation of 11 pounds. Test the validity of this claim at α =0.01. (Use t = -2.786.) What is the correct decision and conclusion?

• Reject Ho​ . There is not sufficient evidence to indicate that the average consumption of fresh citrus fruit by families in the Phil. is at least 98 per year.

• Fail to reject Ho​ . There is not sufficient evidence to indicate that the average consumption of fresh citrus fruit by families in the Phil. is at least 98 per year.

• Reject HoHo​ . There is sufficient evidence to indicate that the average consumption of fresh citrus fruit by families in the Phil. is at least 98 per year.

• Fail to reject Ho​ . There is sufficient evidence to indicate that the average consumption of fresh citrus fruit by families in the Phil. is at least 98 per year.

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

Which of the following represents the appropriate null & alternative hypotheses?

The mean height of women is greater than 65"

• H₀: p > 65"

  Hₐ: p ≠ 65"

• H₀: μ > 65"

  Hₐ: μ ≠ 65"

• 
  H₀: p = 65"

  Hₐ: p > 65"

• H₀: μ < 65"

  Hₐ: μ > 65"

What is the only option for the null hypothesis? 

• H₀ ≠ k

• H₀ = k

• H₀ < k

• 
  H₀ > k

The weight of the average 3rd year student's backpack (with books in it) is 18.4 lbs. The Dean of the school thinks that the backpack does not weight 18.4 lbs. What is the null and alternate hypothesis? 

• 
  H₀ = 18.4
  H_a = 18.4

• 
  H₀ = 18.4
  H_a < 18.4

• H₀ = 18.4
  H_a > 18.4

• H₀ = 18.4
  H_a ≠ 18.4

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

• Find your test statistic

• 
  Check assumptions & conditions

• 
  State your null & alternative hypotheses

• State your conclusion

In a hypothesis test, the alternative hypothesis is always a statement of equality. 

• True

• False