Statistics Normal Probabilities

• Population Mean

• Mean of the Sampling Distribution of X-bar

• Sample Mean

• Proportion

What does this formula do?

• Calculates Standard Deviation

• Checks if the samples are independent

• Checks Normality

• Calculates Probabilities

Which two factors prove that the sampling distribution of X-bar is approximately normal?

• n(p) >= 10 and n(1-p) >=10

• the population is stated as approximately normal

• n is greater than or equal to 30

• the population is stated as symmetric

Select the correct description

• Mean of the Sampling Distribution of p-hat

• Population Mean

• Percents of Means

• Proportions

The weights of paper discarded each week by households are normally distributed with a mean of 9.43 pounds and a standard deviation of 4.17 pounds.  What percent of households throw out fewer than 2 pounds of paper each week?

• 96.26%

• 48.13%

• 3.74%

• 1.87%

The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a standard deviation of 3 days.

About what percent of the products last between 12 and 15 days?

• 68%

• 34%

• 16%

• 2.5%

The weight of infants at a daycare is normally distributed with a mean of 10 lbs and a standard deviation of 1.7 lbs. What is the probability a randomly selected baby weighs 8.1 lbs or less?

A manufacturer contracts to supply ball bearings with diameters between 24.60mm and 25.4mm. Product analysis indicates that the ball bearings manufactured have diameters that are normally distributed with a mean of 25.10mm and a standard deviation of .20mm. What percentage of ball bearings fail to satisfy the contract specifications?

• 92.7%

• 7.3%

• 48.2%

• 33.2%

Find the area of the shaded region. 

• 0.16

• 0.84

• 0.68

• 0.34

What is the probability that the value of a standard normal random variable z lies between 0 and 1.28?