Random vs Population Mean

Another word for average is

• sample 

• mean

• data

• numerical data

A tire manufacturer claims that one particular type of tire will last at least 50,000 miles.  A group of angry customers does not believe this is so.  They take a sample of 14 tires to test if the mean mileage of the tires is really less than 50,000. 
What set of hypotheses are they interested in testing?

• H0: μ = 50,000 vs. Ha: μ < 50,000

• H0: x̅ = 50,000 vs. Ha: x̅ < 50,000

• H0: μ = 50,000 vs. Ha: μ ≠ 50,000

• H0: μ = 50,000 vs. Ha: μ > 50,000

A medical researcher measured the pulse rates (beats per minute) of randomly selected adults and found the following t-based confidence interval:
With 90.00% Confidence,
71.12512 < μ(Pulse) < 73.28914
What is the correct interpretation of the t-interval? 

• We are 90% confident that the true, population mean of pulse rates is between 71.12512 and 73.28914 beats per minute.

•  We are 90% confident that the true, population proportion of pulse rates is between 71.12512 and
  73.28914 beats per minute.

• We are 90% confident that the sample proportion of pulse rates is between 71.12512 and 73.28914
  beats per minute.

• We are 90% confident that the sample mean of pulse rates is between 71.12512 and 73.28914 beats
  per minute.

• A) Randomization Condition
• B) 10% Condition
• C) Independent Samples Condition
• D) Nearly Normal Distribution Condition

If the mean of a sample is 203 and the margin of error is 4.6, what would be a reasonable mean for the population?

• 99.2

• 198.3

• 207.2

• 207.7

A survey of 200 students at a high school finds that the average amount of money spent on lunch per week is $25 with a margin of error of ±5. Estimate the total amount of money spent by all students at the high school on lunch per week if there are 1200 students.

• $15,000-$20,000

• $24,000-$36,000

• $770

• $40,000

Do you expect that this mean of 5 is the same as the true population mean?

• Yes

• No

A quality control inspector will measure the salt content (in milligrams) in a random sample of bags of potato chips from an hour of production. Which of the following would result in the smallest margin of error in estimating the mean salt content μ?

• 90% confidence; n = 25

• 90% confidence; n = 50

• 95% confidence; n = 25

• 95% confidence; n = 50

• n=100 at any confidence level

In a sample of 50 people in a town, the average yearly consumption of fruits is found to be 75 kilograms with a margin of error of 10 kilograms. Estimate the total yearly consumption of fruits in kilograms for the town's population of 2000 people.

• 130,000 kg-170,000 kg

• 110,000 kg-120,000 kg

• 180,000 kg- 200,000 kg

• 130 kg- 170 kg

• 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.