1. 2.1-2.2 Frequency Distributions and Histograms
Advanced Math Topics
Frequency Distributions and Histograms

2. You placed an ad on Craigslist to sell your old car
You placed an ad on Craigslist to sell your old car. The following bids were received. Construct a frequency distribution and histogram of the data.
$3200
$2375
$3440
$3500
$3230
$3475
$3550
$3600
$4000
$3300
$3480
$3525
$3750
$3800
$3400
$3950
$3430
$3840
$3925
$3625
$3575
$3250
$3980
$3700
$3350
$3900
$3375
$3975
Frequency distribution-a table that groups data to show meaningful patterns
(you can use singletons or intervals)
Histogram(frequency histogram)- a bar graph that has intervals on the horizontal
axis and the frequency on the vertical axis
All histograms are bar graphs but not all bar graphs are histograms…

3. Frequency Table $3200 $2375 $3440 $3500 $3230 $3475 $3550 $3600 $4000
$3300
$3480
$3525
$3750
$3800
$3400
$3950
$3430
$3840
$3925
$3625
$3575
$3250
$3980
$3700
$3350
$3900
$3375
$3975
1) Find the least and greatest numbers.
2) Between 5 and 15, pick the number of intervals…let’s use 10 intervals.
Round, make it easier!
3) Find the size of the interval by…
largest value – smallest value
4000 – 2375
1625 = = =
162.5 =
165
# intervals 10 10

4. These are the main columns!! 1 2 3 4 5 6 7 8 9 10 Class # Class Mark
Class(Interval)
Car Offers
Class Mark
Tally
Frequency
Relative Frequency
average 1
$2375-
2539
2457 I 1
1/50
$165 2
$2540-
2704
2622 3
$2705-
2869
2787
These are the main
columns!! 4
$2870-
3034
2952 5
$3035-
3199
3117 6
$3200-
3364
3282
IIIII IIIII III 13
13/50 7
$3365-
3529
3447
IIIII III 8
8/50 8
$3530-
3694
3612
IIIII IIIII 10
10/50 9
$3695-
3859
3777
IIIII IIII 9
9/50 10
$3860-
4024
3942
IIIII IIII 9
9/50
Helps us talk about
classes easier!
Class Frequency
total frequency
Class Average
(midpoint)
Lower limit-upper limit

5. Rules for Drawing Histograms
Intervals are of equal size (except possibly the end intervals)
The # of intervals should be 5 through 15
Intervals do not overlap. If an interval ends with a counting #, the following interval begins with the next #
Any tally falls into 1 and only 1 interval
Bars are next to each other. There are no gaps unless an interval has a frequency of 0

6. This histogram could help us make decisions about selling our car!! 13
9/50 is the relative frequency
AND 9/50 is the area of this rectangle
compared to the total blue area.
The area under any rectangle
compared to the total rectangle area
is proportional to the relative
frequency. 12 11 F R E Q U N C Y 10 9
The area of any combination of
rectangles is proportional to the
sum of their relative frequencies. 8 7 6 5
Add these fractions together to
get 21/50. This is also the sum of the
areas of both rectangles divided by the
total area of all rectangles.
8/50
9/50
13/50 4 3 2 1
$2375-
$2540-
$2705-
$2870-
$3035-
$3200-
$3365-
$3530-
$3695-
$3860-
2539
2704
2869
3034
3199
3364
3529
3694
3859
4024
This histogram could help us make decisions
about selling our car!!
Car Offers

7. Here is my tallying suggestion:
$2375-
2539
$3200
$2375
$3440
$3500
$3230
$3475
$4000
$3550
$3300
$3600
$3480
$3525
$3800
$3400
$3950
$3430
$3840
$3750
$3625
$3575
$3250
$3980
$3700
$3900
$3375
$2540-
2704
$2705-
2869
$2870-
3034
$3035-
3199
$3200-
3364
$3365-
3529
$3530-
3694
$3695-
3859
$3860-
4024

8. From Assignment 2A Together…
P. 39 #16

9. 57 83 41 55 59 7 77 75 79 84 46 68 38 70 82 53 45 60 10 54 23 47 56 61 21 78 74 42 97 65 28 67 32 86 31

10. HW P #1, 4, and 16
For #4 do the complete table, for #16 do only the interval and frequency. Create a histogram for both.