Descriptive Stats
This measure represents the average of a data set.
Mean
If order matters when counting outcomes, this counting method is used.
permutations
A z-score tells how many of these a value is from the mean.
standard deviations
The graph of a normal distribution is commonly called this shape.
Bell Curve
In a deck of 52 cards, this is the probability of drawing a heart.
1/4 (25%)
This measure is the middle value when data are arranged from least to greatest.
Median
If order does not matter when selecting items, this method is used.
combinations
A z-score of 0 means the value is located here.
The mean
In a normal distribution, approximately this percent of data lies within 1 standard deviation of the mean.
68%
The probability of an event that cannot happen is this number.
0
This measure is the value that occurs most often in a data set.
Mode
How many ways can 5 students line up for lunch?
120 (5!)
If a value has a z-score of +2, it lies this many standard deviations above the mean.
2
Approximately this percent of data lies within 2 standard deviations of the mean?
95%
The probability of an event that is certain is this number.
1
This statistic is found by subtracting the smallest value from the largest value.
Range
How many ways can you choose 3 officers from 10 students if the positions are president, vice president, and secretary?
720 (10P3)
Find the z-score for a score of 80 if the mean is 70 and the standard deviation is 5.
2
Approximately this percent of data lies within 3 standard deviations of the mean.
99.7%
You flip a fair coin 3 times. What is the probability of getting exactly 2 heads?
3/8
This measure describes the average distance that data values are from the mean.
Standard deviation
How many ways can 4 pizza toppings be chosen from 10 available toppings?
210 (10C4)
A student scores 65 on a test with a mean of 75 and a standard deviation of 5. Find the z-score.
-2
According to the Empirical Rule, what percent of data lies between 1 and 2 standard deviations from the mean on both sides combined?
27%
If the probability of rain tomorrow is 0.30, what is the probability that it will not rain?
0.70 (70%)