Statistics Concepts Normal Distribution

Which is NOT true about the normal distribution curve?

• It is bell-shaped.

• The mean, median, and mode are approximately equal

• The smaller the standard deviation, the less spread in the curve.

• It is asymmetrical.

According to the empirical rule, what percentage of data falls within 1 standard deviation? 

• 25%

• 68%

• 95%

• 99.7%

What is the Normal Range (68%) of the annual precipitation for Phoenix, if the average is 29 with a standard deviation of 3?

• 26-32

• 3-29

• 26-29

• 39-32

What's the probability of the gray area? (Mean = 55, Standard dev = 2.5)

• 0.8185

• 0.8413

• 0.8641

• 0.8389

What's the probability of the highlighted area?

(Mean = 30, Variance = 1)

• 0.8664

• 0.7863

• 0.9332

• 0.8754

What's the probability of the highlighted area? (Mean = 100, Standard dev = 10)

• 0.9772

• 0.0228

• 0.1587

• 0.0062

What's the probability of 49 < x < 51 ?

(Mean = 50, Standard dev = 6.5)

• 0.1192

• 0.1251

• 0.1587

• 0.0875

If you had to guess the probability of the gray area, which would you choose?

• 0.2

• 0.4

• 0.6

• 0.8

If the value we are looking for is smaller than the mean, the value of z is:

• Not enough information

• Negative

• Positive

• 0

If the value we are looking for is the same as the mean, the value of z is:

• Not enough information

• Positive

• Negative

• 0