Central Limit Theorem and Sampling Distributions with Means

Which of the following is a true statement?
A.  The larger the sample, the larger the spread in the sampling distribution.
B.  Statistics from smaller samples have less variability.
C.  The sampling distribution always matches the shape of the parent population.
D.  The sampling distribution gets more narrow, as the sample size increases.

• A
• B
• C
• D

What is the purpose of using a random method to get a sample?

• A.  Reduce bias.
• B.  Reduce variability.
• C.  Increase bias.
• D. Increase variability.

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.3

Researches found that boys playing high school football absorb an average of 355 hits to the head with a standard deviation of 80 hits during a season.  What is the probability on a randomly selected team of 48 players that the average number of head hits per player is between 340 and 360?

• .236
• .429
• .571
• .614

Suppose the teenagers that attend public high schools get an average of 5.7 hours of sleep each night with a standard deviation of 1.7 hours.  What is the probability that a randomly selected group of 35 high school students get more than 6 hours of sleep each night?

• .430
• .148
• .281
• .087

The amount of fuel used by jumbo jets to take off is normally distributed with a mean of 4000 gallons and a standard deviation of 125 gallons.  What is the probability that the mean number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3950 gallons?

• .121
• .299
• .345
• .781

• A
• B
• C
• D