Statistics Normal Distribution

A data set has a mean of 290 and a standard deviation of 20. Calculate the z-score for an x value of 265.

What is the standard deviation on this Normal Curve?

• 6

• 12

• 34

• 18

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

• Not enough information

• Positive

• Negative

• 0

Z-score of 2.5 on an IQ test is considered a genius (mean=100, SD=16). What score makes someone a genius?

• 89.2

• 130

• 99.38

• 140

μ = 70 , σ = 8 , X = 50 . Find z score

• 2.5

• -2.5

• 5.2

• -5.2

Which is NOT true about the standard normal distribution?

• It is bell-shaped.

• It is unimodal.

• The mean is 0 and the standard deviation is 1.

• It is asymmetrical.

If I tell you that you scored at the 55th percentile on your final exam, you would know:

• 55% of the class scored the same or worse than you did

• You earned a 55% on the exam

• You failed the exam

• 45% of the class scored worse than you did

What percent is represented by the area between 0 and 1?

• 68%

• 34%

• 95%

• 47.5%

The area under a normal distribution between z = –2 and z = 1 is

• ≈ 68%

• ≈ 82%

• ≈ 95%

• ≈ 97%

What percent of a normal distribution lies outside of ±3 standard deviations?

• .15%

• 100%

• .3%

• 99.7%