Praxis Core Math
- Data representations | Lesson
- Data representations | Worked example
- Center and spread | Lesson
- Center and spread | Worked example
- Random sampling | Lesson
- Random sampling | Worked example
- Scatterplots | Lesson
- Scatterplots | Worked example
- Interpreting linear models | Lesson
- Interpreting linear models | Worked example
- Correlation and Causation | Lesson
- Correlation and causation | Worked example
- Probability | Lesson
- Probability | Worked example
What are the center and spread of a data set?
A set of quantitative data with varying values may be shown as a list or a data display.
Suppose Pedro asks
friends how many pairs of shoes they own. Pedro can report his findings as a list or a data display such as a dotplot where each dot represents one response.
Center and spread are ways to describe data sets like this.
- Center describes a typical value of a data point. Two measures of center are mean and median.
- Spread describes the variation of the data. Two measures of spread are range and standard deviation.
What skills are tested?
- Calculating the mean, median, and range from a list of values or a data display
- Comparing the mean, median, range, and standard deviation of data sets. You won't be tested on the formula for standard deviation.
How is the median calculated?
The median is useful to describe the center of data with .
The median is the middle value when the data are ordered from least to greatest.
- If the number of values is odd, the median is the middle value.
- If the number of values is even, the median is the average of the two middle values.
How is standard deviation used ?
Standard deviation measures the typical spread from the mean.
Standard deviation is the average distance between the mean and a data point.
Larger values of standard deviation indicate greater spread in the data.
TRY: FINDING THE MEDIAN
|Station Number||Gas Price (per gallon)|
gas stations near his house.
The price of gas at each station is shown in the table above. What is the median price of gas at the stations Tomas visited?
TRY: CALCULATING THE MEAN
A veterinary student is studying newborn giraffes. The list above shows the masses of
newborn giraffes, rounded to the nearest kilogram. What is the mean mass of the newborn giraffes?
Round you answer to the nearest kilogram.
TRY: CALCULATING THE RANGE
Tayo got the following scores on her Spanish quizzes:
. What is the range of Tayo's quiz scores?
TRY: FINDING THE MEDIAN USING A DATA DISPLAY
The dotplot above shows the volume of juice squeezed from
oranges. What is the median volume of juice squeezed, in fluid ounces?
Things to remember
Center describes a typical value.
- Mean: Average value
- Median: Middle value when data ordered from least to greatest
Spread describes the variation of the data.
- Range: Total spread
- Standard deviation: Average distance between the mean and a data point
Want to join the conversation?
- gaergargasfgacvxbcxbxvbdgbdrtgbfgse srgsergerce e ge(4 votes)
- What is standard deviation?(2 votes)
- You need to know the Mean or Average of the data points. Standard deviation is difference between a data point and the mean.(2 votes)
- What about the mode in things to remember? Is that not a typical question on the Praxis?(1 vote)