# STAT

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1. WHAT IS THE NORMAL DISTRIBUTION?
IS A CONTINOUS PROBABILITY DISTRIBUTION FOR A GIVEN RANDOM VARIABLE, X, THAT IS COMPLETELY DEFINED BY ITS MEAN AND STANDARD DEVIATION
2. A NORMAL DISTRIBUTION IS DEFINED BY ITS
MEAN AND STANDARD DEVIATION
3. NORMAL DISTRIBUTIONS ARE ALL BELL SHAPED. THE MEAN, MODE, AND MEDIUM ARE ____.
ALL THE SAME VALUE.
4. THE MEAN/MEDIUM/MODE IS LOCATED AT THE CENTER OF A DISTRIBUTION
MEAN
5. WHAT DETERMINES THE SHAPE OF THE CURVE?
STANDARD DEVIATION
6. WHAT IS THE STANDARD DEVIATION
• DISTANCE FROM THE MEAN TO ONE OF THE INFLECTION POINTS
• The standard deviation is a statistic that tells you how tightly
• all the various examples are clustered around the mean in a set of data.
• When the examples are pretty tightly bunched together and the
• bell-shaped curve is steep, the standard deviation is small. When the
• examples are spread apart and the bell curve is relatively flat, that
• tells you you have a relatively large standard deviation.
7. INFLECTION POINT
IS A POINT ON THE CURVE WHERE THE CURVUTURE OF THE LINE CHANGES
8. The inflection points are either:
• u-o
• u+o
9. 3 identical bell shaped curvatures on one line all have the same ____ but different ____.
• standard deviation
• mean
10. Properties of a normal distribution.
• 1. SYMEMETRIC AND BELL-SHAPED
• 2. COMPLETELY DEFINED BY IT'S MEAN, U, AND STANDARD DEVATION, O
• 3. TOTAL AREA UNDER CURVE IS =1
• 4. CURVE DOES NOT CROSS OR TOUCH X AXIS
11. SYMBOLS U AND O
• U - MEAN
• O- STANDARD DEVATION
12. Properties of a Standard Normal Distribution

*special version of the normal distribution
Has the same properties as the normal distribution but always has a MEAN OF 0, and a STANDARD DEVIATION of 1
13. What kind of curve is this?
Mean- 0
Standard deviation- 1
Standard Normal Distribution
14. The larger the standard deviation, the _____ area there will be in the tail of the distribution.
Why
• More area
• The curve will appear flatter
• Because the standard deviation determines the height of the bell shaped distribution
15. PROBABILITY CERTAINLY EQUALS
WHY IS X<x
• 1
• X= THE PROBABILITY, WHICH MUST BE EQUAL OR LESS THAN 1
16. What does the z score do?
The z score is a formula t/f
transforms a normal random variable into a standrard normal random variable.

True

Z= x-u / o
17. HOW WOULD YOU WORD THE EQUATION OF A PROBABIILTY THAT IS BETWEEN 659-1530. WHICH WAYS ARE THE SYMBOLS FACING?
• P (659 < X < 1530)
• <------ TO THE LEFT
18. THE CUMMULATIVE STANDARD NORMAL TABLE GIVES US THE ANSWERS FOR PROBABILITYS OF THE LEFT/RIGHT OF Z.
LEFT
19. TABLE TO LOOK UP PROBABILITIES
CUMMULATIVE STANDARD NORMAL TABLE
20. THE "Z VALUE" CORRESPONDS TO
THE PROBABILITY GIVEN BY THE CHART.
21. GIVEN: X=46.2, U=46 AND O=1.4. INDICATE WHERE ON THE CURVE THE X VALUE WOULD BE.
• IT WOULD BE ON THE HORIZONTAL LINE, AFTER 46
• 40.4_________46___X________51.6
22. What does the z score do?
The z-score (z) can transform a normal random variable into a standard normal random variable.

• z= X-U
• ------------
• O
 Author: bettyvillagomez ID: 78128 Card Set: STAT Updated: 2011-04-08 17:31:02 Tags: BEGINNING STATISTICS Folders: Description: UNIT 3 Show Answers: