Normal Distributions and Central Limit Theorem

What is the standard deviation of the sampling distribution?

• 200

• 25

• 20

• 5

• 4

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?

• Approximately 0.0418

• Approximately 0.09

• Approximately 0.57

• Approximately 0.67

• Approximately 0.9582

Find the area of the shaded region if the z-score is 0.75

• 0.2266

• 0.7734

• 0.758

• 0.242

Find the area of the shaded region if the z-scores are -2 and -0.5

• 0.6915

• 0.3085

• 0.0228

• 0.2857

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?

• 0.0057

• 0.025

• 0.345

• 0.781

• 0.9943

The weights of the eggs produced by a certain breed of hen are normally distributed with mean 65 grams and standard deviation of 5 grams. What is the probability that one egg selected at random from a hen house will weigh more than 68 grams?

• 0.2743

• 0.7257

• 0.0901

• 0.9099

What happens to the shape of a sampling distribution of sample means as n increases?

• The skew gets bigger

• The skew is reversed

• It becomes narrower and more normal.

• The shape is the same, but wider

These symbols represent the mean and standard deviation for which of the following distributions?

• The Population

• The Sample

• The sampling distribution (mean)

• The sampling distribution (proportion)

What is the standard deviation of the distribution?

• 1010

• 60

• 40

• 20

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?

• Approximately 0.15

• Approximately 0.43

• Approximately 0.57

• Approximately 0.85