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Finding Z Score
Using Z Score
Describing Density Curves
Empirical Rule
Miscellaneous
100
Find the z score if x = 60, mean = 65, and standard deviation = 2.5
-2
100
What percent of the data is below a z-score of 0.63?
73.6%
100
Describe the density curve. (See Figure A)
Normal Curve
100
What is the other name for the Empirical Rule?
68-95-99.7 Rule
100
Which of the following is the symbol for standard deviation A. μ B. Ω C. σ D. Σ
C. σ
200
Find the mean when z = 3, x = 70, and standard deviation = 4
58
200
What is the area under the standard curve corresponding to Z < 1.31?
.90490
200
Describe the density curve. (See Figure B)
Skewed left
200
IQ Scores have a normal distribution with a mean of 100 and a standard deviation of 12. What percentage of IQ scores are between 76 and 124?
95%
200
The area under a normal curve is always ____ .
One
300
Find x when z = 1.5, standard deviation = 3, and mean = 50
54.5
300
What is the area under the standard curve corresponding to Z > 0.05?
.51994
300
Describe the density curve. (See Figure C)
Skewed right
300
Heights of women aged 18-24 are approximately normal with mean 64.5 and standard deviation 2.5. Between what heights does 68% of the data fall?
62-67 in
300
Which of the following is the equation for Z score? A. (x - σ) / μ B. σ / (x - μ) C. (μ - σ) / x D. (x - μ) / σ
D. (x - μ) / σ
400
Find standard deviation when z = 2.5, x = 60, and mean = 55
2
400
What is the area under the standard curve corresponding to -.0.4 < Z < 1.9?
.6267
400
In a skewed left density curve what is the relationship between the mean and median?
Mean is to the left of the median.
400
About 68% of seniors scored between 390 and 590 on an SAT verbal test. What is the mean and standard deviation of this data set? (assuming that the distribution is approximately normal)
Mean= 490; Standard deviation= 100
400
The mean in Z score is always ____.
Zero
500
If the z score = -4.5, x = 15, and mean is three times x, what is the standard deviation?
6.66
500
Scores on the ACT test for the 2004 high school graduating class had a mean of 20.9 and a standard deviation of 4.8. In all, 1,171,460 students in this class took the test, and 1,052,490 of them had scores of 27 or lower if the distribution of scores were normal, what percent of scores would be 27 or lower? What percent of actual scores were 27 or lower? Does the normal distribution describe the actual data well?
Table Percentage: 90% Actual Percentage: 90% Yes
500
In a skewed right density curve what is the relationship between the mean and median?
Mean is to the right of the median.
500
Scores on an ACT test had a mean of 20.9 and a standard deviation 4.8. What percent of students scored 35.3 or higher?
0.15
500
What is the point of a density curve that divides the area under the curve in half?
The median