Chapter 1

Unit QuestionHow do numbers measures, graphical

representations and expressions represent mathematical situations?

Open Learning Logs

Date on Left…Section 1 – 6 on right

Make a list of everything you can remember about statistics from last year

1 – 6 Warm – Up

Section 6

How do we calculate and use the measures of central tendency?

Homework Check

Measure of Central Tendency:A value to illustrate where data are centered

Mean:Average of the data (add ‘em up and divide!)Used when there are NO outliers

Median:Middle number of a set of data when the numbers are in orderUsed when outliers exist

Mode:The piece of data that appears the most

Outlier:A piece of data way outside the other values of data

Definitions…

Find the Mean, Median and Mode…

The wages of employees at a local restaurant are shown

$6.25 $6.50 $6.75 $7.00 $7.25 $7.50 $7.75 $8.00 $8.25 X XX

XXX

XXXX

Mean: 6.6108.257.003(6.50)5(6.25)

Median: 6.25 6.25 6.25 6.25 6.25 6.50 6.50 6.50 7.00 8.25

375.6250.625.6

Mode: 6.25

Which is the best measure of central tendency and WHY?

Median:

Mode:

SOLVE!!!

Suppose your grades on three history exams are 80%, 93%, and 91%. What grade do you need on your next exam to have a 90% average on the four exams?Let x = the fourth exam score

904919380

x

904264

x

90442644

x

360264 x264 264

96x

You would need a 96% on the last exam to average 90%.

Definitions:

Stem and Leaf Plot: graph that uses PLACE VALUE for data

Range: the difference between the greatest and least values

Range = Max – Min

READY?

Let’s do it…

The city and highway mileage for 9 new cars are listed…

CITY19, 31, 34, 20,

29, 31, 28, 23, 23

HIGHWAY41, 30, 27, 38

38, 28, 32, 37, 32

1234

90 3 3 8 91 1 4

1234

7 80 2 2 7 8 81

Sometimes a “back-to-back” stem and leaf is useful…Next slide please

CITY19, 31, 34, 20,

29, 31, 28, 23, 23

HIGHWAY41, 30, 27, 38

38, 28, 32, 37, 32

1234

90 3 3 8 91 1 4

1234

7 80 2 2 7 8 81

1234

7 80 2 2 7 8 81

99 8 3 3 0

4 1 1

What is the range of City mileage?151934

32

32 AND 38

What is the median of Highway mileage?

What is/are the mode(s) of highway mileage?

Homework

• Do HoffmaSheet 1 – 6