7th grade math Flashcards
the sum of the data values divided by the number of data items
mean
the middle value of an odd number of data items arranged in order
median
What do you do to find the median of an even number of data items?
the median is the mean of the two middle numbers
the value or values that occur most often
mode
What is the mode if the data values occur the same number of times?
There is no mode.
the difference between the greatest and the least values
range
Find the mean of the following numbers:
2,1,8,0,2,4,3,4
mean = 24/8 = 3
Find the median of the following numbers:
2,1,8,0,2,4,3,4
0,1,2,2,3,4,4,8 - even
The two middle numbers are 2 and 3
2+3 = 5 5/2 = 2.5
Find the mode of the following numbers:
2,1,8,0,2,4,3,4
0,1,2,2,3,4,4,8
The modes are 2 and 4 because they both occur twice.
Find the range of the following numbers:
2,1,8,0,2,4,3,4
0,1,2,2,3,4,4,8
largest - smallest 8-0 = 8
What are the measures of central tendency?
mean, median, mode
What is the meaning of measuring central tendency?
finding the middle
When is mean most useful?
when the data are spread evenly
When is the median most useful?
when the data set has an outlier
When is mode most useful?
when knowing which data point receives the most is important like in an election
an extreme value very different from the others
outlier
using a number line to show the distribution of a set of data
box-and-whisker plot
In a box-and-whisker plot, the median of the lower half is called what?
lower quartile
In a box-and-whisker plot, the median of the upper half is called what?
upper quartile
the difference between the lower and upper quartiles or the length of the box
interquartile range
the smaller the interquartile range tells us what about the data
more predictable
what is an entire group called
population
what is a part of a population called
sample
when samples are chosen where everyone has an equal chance of being chosen
random sample
when samples are based upon individuals that are readily available
convenience sample
a sample that doesn’t fairly represent the population
biased sample
why would you want to use a sample instead of the entire population
if population is large
why is it difficult to get a truly random sample
not convenient
