Normal Probability Distributions

Standard Normal Distribution (mean is 0 and standard deviation is 1).  Find the score that separates the lowest 98% from the highest 2%.

• - 2.05
• 2.05
• -1.95
• 1.95

6.2: Uniform distribution:  Suppose your phone battery can last anywhere between 2 hours and 8 hours depending on use. If the amount of time it lasts is distributed uniformly, what is the probability that the battery lasts less than 4 hours?

• 1/6
• 1/4
• 1/3
• 1/2

6.2:  Standard Normal Distribution (mean is 0 standard deviation is 1).  For a randomly selected subject, find the probability of a score between 1.37 and 2.42.

• 0.078
• 0.785
• 0.223
• 0.023

6.3:  Non-Standard Normal Distribution.  IQ scores are normally distributed with mean 100 and standard deviation 15.  Find the probability of randomly selecting an IQ score above 90.

• 0.683
• 0.748
• 0.715
• 0.796

6.3:  Non-Standard Normal Distribution.  IQ scores are normally distributed with a mean of 100 and standard deviation 15.  Find the IQ score separating the bottom 85% from the top 15%.

• 135
• 125
• 120
• 115

6.5 CLT:  Red blood cell counts of women are normally distributed with a mean of 4.577 and a standard deviation of 0.382.  Find the probability that one randomly selected woman has a red blood cell count above 5.4.

• 0.150
• 0.0156
• 0.215
• 0.0237

6.5 CLT:  Red blood cell counts of women are normally distributed with a mean of 4.577 and a standard deviation of 0.382.  What percentage of women have red blood cell counts in the normal range from 4.2 to 5.4?

• 82.3%
• 77.8%
• 72.6%
• 68%

6.5 CLT:  Red blood cell counts of women are normally distributed with a mean of 4.577 and a standard deviation of 0.382.  If 25 women are randomly selected, find the probability that the mean of their red blood cell counts is less than 4.444.

• 0.409
• 0.0409
• 0.368
• 0.0368

6.2:  z-alpha notation (shade right):  Using z-alpha notation, find the z-score for z (sub).45:

• 0.145
• 0.126
• 0.137
• 0.189

6.7 Binomial:  Use the continuity correction and describe the region of the normal distribution that corresponds to the probability of exactly 44 green marbles.

• The area between 43.5 and 45.5
• The area between 43.5 and 44
•  The area between 43.5 and 44.5
• The area between 44 and 44.5