Mean and Standard Deviation from Probability Distribution

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?

• .0057

• .025

• .345

• .781

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 mean and standard deviation of a population are 400 and 40, respectively. Sample size is 25. 
What is the mean of the sampling distribution?

• 400

• 40

• 25

• 8

The mean and standard deviation of a population are 400 and 40, respectively. Sample size is 25. 
What is the standard error of the sampling distribution?

• 400

• 40

• 25

• 8

Following is the probability distribution for the age of a student at a certain public high school.

Find the standard deviation of the probability distribution

• 1.52

• 1.26

• 1.87

• 1.71

The table represents the probability of guessing correct on a 5 question true-false quiz. Find the mean and the standard deviation.

• μ = .4; σ = 7.5

• μ = 2.5; σ = 1.1

• μ = 3; σ = 1.3

• μ = .1; σ = 0

What does this symbol represent?

• Median

• Variance

• Standard Deviation

• Mean Absolute Deviation

The table above shows a television station's advertisement sales. The distribution of sales for one 24-hour day is given. Solve for the standard deviation. Round to the nearest hundredth.

• 45.81

• 266.2

• 16.30

• 0.20

The table above shows the number of cell phones per household in a small town. Find the standard deviation. Round to the nearest hundredth.

• 0.80

• 1.70

• 1.30

• 1.00

Which of the following expressions correctly shows an expected value calculation for the probability distribution below?