Calculating Probabilities with the Normal Distribution

What is the total area under a normal distribution curve?

• None of the above

• 0.5 or 50%

• 1 or 100%

• 0 or 0%

What is the mean (µ) of the standard normal distribution?

• 1

• 0

• -1

• 100

How is the z-score calculated from any normal distribution score x?

• z = μ/σ

• z = (x-μ)/σ

• z = (x-μ)×σ

• z = (x+μ)/σ

What does the 'Less Than' cumulative table typically show?

• No shading

• Both tails shaded

• Right tail shaded

• Left tail shaded

What is the probability that x is less than 54?

• 0.4448 or 44.48%

• 0.3336 or 33.36%

• 0.2224 or 22.24%

• 0.1112 or 11.12%

What is the z-score for x = 80?

• 0.56

• 1.67

• 1.22

• 2.33

What is the probability that x is at least 80?

• 0.9901 or 99.01%

• 0.7123 or 71.23%

• 0.9525 or 95.25%

• 0.0475 or 4.75%

What is the probability that x is between 70 and 86?

• 0.2778 or 27.78%

• 0.9901 or 99.01%

• 0.7123 or 71.23%

• 0.0475 or 4.75%

How do you find the area between two z values using the cumulative Less Than table?

• Multiply the two areas

• Subtract the smaller area from the larger one

• Divide the larger area by the smaller one

• Add the two areas

What should you do to find a 'greater than' area using the cumulative Less Than table?

• Add 1 to the area

• Subtract the area from 1

• Multiply the area by 2

• None of the above