Transcript Central Tendency

Mean, Median, Mode
Reference pages 101-105
3.1 E.Q. How do you calculate the
measures of central tendency?
Mean:
1. Add the data
2. Divide the sum by
the number of values
89+ 95+81+81+79=
425 ÷ 5= 85
Central
Tendency
Find the mean:
3, 2, 1, 1, 1, 5, 3, 1, 2, 2
Central
Tendency
Median:
1. Put the numbers in order.
2. Find the middle value.
3. If there are an even # of
values, find the mean of
the middle two.
Central
Tendency
79, 81, 81, 89, 95
Find the mean:
Find the median
3, 2, 1, 1, 1, 5, 3, 1, 2, 2
1111222335=2
Central
Tendency
Mode:
1. Put the numbers in order.
2. Find the number that
happens the most.
79, 81, 81, 89, 95
Central
Tendency
Find the mean:
Find the median
Central
Tendency
Find the mode
3, 2, 1, 1, 1, 5, 3, 1, 2, 2
Central
Tendency
Range:
Subtract the lowest
value from the
highest value.
95-79=
Find the mean:
Find the median
Central
Tendency
Find the mode
Find the range
3, 2, 1, 1, 1, 5, 3, 1, 2, 2
Russell’s homework grades are the
following: 88, 96, 100, 74, 92. Russell
forgot to turn in today’s assignment, so a
zero is recorded for his next homework
grade. How will the zero change his
homework average?
1. Russell’s grade before the zero=?
2. Russell’s grade after the zero=?
E.Q. (2) How do you determine when to
use mean, median, and mode to
represent your data best?
Reference Pages 103-104
Eldon Fig’s midterms are coming out at the
end of the week. His momma will ground
him if he brings home anything less than a
B. Here are his grades. Does he need to
save his money for a bus ticket out of
town?
89, 95, 81, 81, 79
Mean:
Median:
Mode:
Which works out better for Eldon?
How do we know which to use when?
Mean: use when there are no outliers to
distort the data.
Median: use when there are outliers
distorting the data or to describe the
middle value.
Mode: use when the data are not
numerical or you are choosing the
most popular (fashionable) item.
Indian Trail Middle School is having a
competition involving scooters, racing, and
pie. Mrs. Pearce has decided the 7th grade
team with the lowest average of detentions
per week will get to witness the spectacle.
The brilliant Bobcats have collected the
following number of detentions.
16, 20, 18, 22, 22, 19, 21
What measure of central tendency best
reflects the Bobcats’ behavior?
Sixteen 12-year-old girls were asked how many pairs
of earrings they own. The results are below.
23, 27, 12, 20, 11, 9, 5, 10, 16, 32, 14, 31, 13, 8, 37, 32
Mean:
Median:
Mode:
Which one better represents the data?
The median is the better representative. The mean is a
little higher and does not represent the smaller
values as well.
Mean:
Median:
Mode:
Which one better represents the data?
The mean and median are both reasonable.
Mean:
Median:
Mode:
Which one better represents the data?
The mean and median are both reasonable.
The daily attendance at a science fair that
ran for one week is listed.
145, 146, 70, 150, 151, 234, 70
Which average best represents the
attendance?
The median best represents the
attendance for the science fair.