Normal Probability Distribution

For a randomly selected subject, find the probability of a Z-score between 1.37 and 2.42.

• 0.078

• 0.785

• 0.223

• 0.023

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

The hourly wage at a factory is normally distributed with a mean of $12.50 with a standard deviation of $2. The probability that a wage is between $10 and $15 is given by:

• 0.8413

• 0.6826

• 0.8944

• 0.9890

• 0.7888

A standard normal curve is a normal probability distribution that has a standard deviation of ____ and a mean of ____.

• 1, 0

• 0, 1

• 0, 0

• 1, 1

The average size of a marble manufactured at the factory is 0.865in. with a standard deviation of 0.015in. During quality control you find a batch of marbles that average 0.895in. What is the probability of the factory producing marbles that size or larger?

• 2.0%

• 2.1%

• 2.2%

• 2.3%

In a survey of men in the United States (ages 20-29), the mean height was 69.6 inches with a standard deviation of 3.0 inches. Find the minimum height in the top 22%.

• 69.37 in 

• 67.58 in 

• 73.12 in 

• 71.92

Standard Normal Distribution (mean is 0 and standard deviation is 1).  What Z-score would be less than only 2% of the data?

• - 2.05

• 2.05

• -1.95

• 1.95

The scoring of modern IQ is such that Intelligence Quotients (IQs) have a normal distribution of μ= 100 and 𝞂 = 15.

Mensa International is a non-profit organization that accepts only people with IQ score within the top 2%. What level of IQ qualifies one to be a member of Mensa?

• 115

• 130.8

• 145

• 120

What's the probability x < 13?

(Mean = 10, Standard deviation = 2)

• 0.9332

• 0.2266

• 0.7734

• 0.0668

What's the probability x > 17?

(Mean = 15, Standard dev = 3)

• 0.7486

• 0.7454

• 0.2514

• 0.2546