2 sample confidence intervals and hypothesis tests for means

In a two-sample hypothesis test with independent samples...

• ...one sample is used to obtain an estimate, the other sample is used to test a hypothesis.

• ...each sample is used to perform a hypothesis test and the best of the two answers is used.

• ...a comparison is done of the same parameter in two separate populations.

• ...a joint hypothesis test of the population mean and population variance is done.

What distribution do we use when testing claims about population means?

• F

• Z

• t

• Chi

Tags

CCSS.HSS.ID.A.4

Researchers claim that a blue background enhances creativity based on the average scores below. Test the claim at a 1% significance level.

• P = .0021

  We are more creative with blue.

• P = 0.9979

  We are more creative with blue.

• P = .0021

  We are more creative with red.

• P = 0.9979

  There appears to be no difference.

Two pain relief medicines are tested on volunteer post-operation patients, randomly assigned to one of the two brands of medicine, as to whether or not mean duration of relief are different. Data is recorded in minutes of pain relief. What is the conclusion of the appropriate hypothesis test for this experiment?

• P < .05 so reject Ho.

• P < .05 so fail to reject Ho.

• P > .05 so reject Ho.

• P > .05 so fail to reject Ho.

• 5% significance level is inappropriate for medical decisions.

What type of test?
It is thought that the average penny is older than the average quarter. The average age of a sample of 50 pennies was 8.72 years with a s = 0.73 years and the average age of 50 quarters was 6.78 years with a s = 0.99 years.

• 2 sample z-test for mean
• 2 sample t-test for mean
• matched pairs t-test
• 2 sample z-test for proportion

Tags

CCSS.7.SP.B.4

A random sample of 425 citizens of Naboo found that 34% support the Galactic Republic. A sample of 585 citizens of Tatooine found that 38% support the Galactic Republic. What test would you use to determine if the the proportions are different?

• A 2 sample z-test for mean 
• A 2 sample t-test for mean
• A matched-pairs dependent sample t-test for mean
• A 2 - proportion z test

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.

Tags

CCSS.HSS.IC.B.4

• A) Ho: The mean number of days 9th grade students absent is equal to the mean number of days 12th grade students are absent.
  Ha: The mean number of days 9th grade students absent is less than the mean number of days 12th grade students are absent.
• B) Ho: The mean number of days 12th grade students absent is less than the mean number of days 9th grade students are absent.
  Ha: The mean number of days 12th grade students absent is equal to the mean number of days 9th grade students are absent.
• C) Ho: The mean number of days 12th grade students absent is equal to the mean number of days 9th grade students are absent.
  Ha: The mean number of days 9th grade students absent is greater than the mean number of days 12th grade students are absent. 
• D) Ho: The mean number of days 12th grade students absent is equal to the mean number of days 9th grade students are absent.
  Ha: The mean number of days 12th grade students absent is less than the mean number of days 9th grade students are absent.

A health researcher was curious if women in India lived longer on average than men in India. They obtained data from a random sample of 216 records of people in India. Results are shown. What is the P-value?

• 0.00526

• -2.58

• 2.58

• 0.0152

120 Brand X oil filters and 90 Brand Y oil filters were tested for milligrams of residue, with the following results. Find a 95% confidence interval for μY - μX.

• (0.96, 1.44)

• B) (0.92, -0.96)

• C) (-1.44, -0.96)

• D) (-1.84, -0.56)

• E) (0.92, 1.48)

Tags

CCSS.HSS.IC.B.4