Math 211: Chapter 3
The Empirical Rule says that if the distribution is unimodal and symmetric, then the percent of observations that will be within two standard deviations of the mean is
95%
An outlier
All of the Above
The mean of a sample
All of the above
The standard deviation
All of the above
To calculate the mean
All of the above
A measurement with a z-score of -1.4 is 1.4 standard deviations above the mean.
False
The Empirical Rule says that if the distribution is unimodal and symmetric, then nearly all of the observations will be within four standard deviations of the mean.
False
The mean is the only representation of the "typical" value of the variable.
False
The arithmetic average of a collection of data is called the
Mean
If you were to sort the data from smallest to largest, the data value that would be right in the middle is the
Median
A measurement converted to standard units is called a z-score
True
A measurement with a z-score of 1.0 is one standard deviation above the mean.
True
Distributions that have larger standard deviations have more observations that are farther from the mean.
True
Distributions that have smaller standard deviations have more observations that are fairly close to the mean.
True
In a symmetric, unimodal distribution, the majority of the observations (in fact, about two-thirds of them) are less than one standard deviation from the mean.
True
Standard units measure a value relative to the sample rather than with respect to some absolute measure.
True
The Empirical Rule says that if the distribution is unimodal and symmetric, then approximately 68% of the observations (roughly two-thirds) will be within one standard deviation of the mean.
True
The mean can be thought of as the balancing point of a distribution of data.
True
The median cuts a distribution down the middle, so about 50% of the observations are below it and about 50% are above it.
True
The median value represents a "typical" value in a data set.
True
The standard deviation is a number that measures how far away the typical observation is from the mean.
True
Two commonly used graphs to display the distribution of a sample of categorical data are bar charts and pie charts.
True
When the distribution of the data is more or less symmetric, the balancing point is roughly in the center.
True
z-Scores allow us to compare observations in one group with those in another, even if the two groups are measured in different units or under different conditions.
True
To convert a value to its z-score
use the formula
