Exam #2 Flashcards
(85 cards)
What are Quartiles?
numbers which divide a set of data into four groups, with about 25% of the values in each group.
The first Quartile is the same as…
25th percentile
The second Quartile is the same as…
50th percentile
The third Quartile is the same as…
75th percentile
What are percentiles?
numbers which divide a set of data into 100 groups with about 1% of the values in each group.
Define Procedure
a process with uncertain results that can be repeated
Define Event
any collection of results or outcomes of a procedure
Define Sample Space
the set of all possible outcomes for a procedure
What does P(A) mean?
The probability of event A occurring
What is the rounding rule for probability?
a probability should always be expressed either as a simple fraction or as a decimal rounded to three significant digits.
What are the three methods for determining probability and which is the most commonly used?
- Relative Frequency Approximation
- Classical Approach (most common)
- Subjective Approach
What is the formula for Relative Frequency Approximation?
P(A)=number of times event A occurred/number of times the procedure was repeated
What is the formula for the Classical Approach?
P(A)=number of ways A can occur (s)/number of possible outcomes (n)
*need a sample set to count the total possible outcomes and the number of outcomes containing the occurrence of A
What is the formula for the Subjective Approach?
no formula - this is an educated guess
for example: what are the chances it will rain tomorrow?
What is the Law of Large Numbers?
As a procedure is repeated again and again, the relative frequency probability tends to approach the actual probability of the event.
(example: the actual probability of flipping heads on a coin is 1/2 or 50%. The more times you flip the coin, the closer you will get to accurate results.)
What is the complement of an event?
The compliment of event A would be the event consisting of all the outcomes in which A does not occur.
What is the probability of an impossible event?
0
What is the probability of a certain event?
1
What is the probability of any event (shown as A)?
0 < P(A) < 1
Define an unlikely event.
an event that has a low probability of occurring. (usually less than or equal to 0.05 or 5%)
Define compound event.
any event combining two or more outcomes.
What does P(A or B)=
the probability of event A or event B occurring
more likely; higher probability
What does P(A and B)=
the probability of event A and event B both occurring
more restrictive; lower probability
In probability, “or” usually indicates…
addition