Statistics 70% of high school teens who use the internet visit

social networking sites, 30% have blogs, and 20% create their own art with online content.

49% of Americans cite a “lot” of stress at age 22, compared with 45% at 42, 35% at 58, 29% at 62, and 20% by 70.

34% of American adults believe in ghosts. 48% of the world’s population lives on less than $2 a

day.

Statistics• A branch of mathematics that provides

techniques to analyze whether or not your data is significant (meaningful)

• The collection, organization, analyzation and interpretation of data

Populations and Samples

A city government wants to conduct a survey among the city’s homeless to discover their opinions about required residence in city shelters from midnight until 6AM.

a.) Describe the population

b.) A city commissioner suggests obtaining a sample by surveying all the homeless people at the city’s largest shelter on a Sunday night. Does this seem like a good idea?

Populations and Samples A city government wants to conduct a survey among the city’s

homeless to discover their opinions about required residence in city shelters from midnight until 6AM.

a.) Describe the population

The set containing all the city’s homelessb.) A city commissioner suggests obtaining a sample by surveying all the

homeless people at the city’s largest shelter on a Sunday night. Does this seem like a good idea?

No; People already in the shelters are probably less likely to be against mandatory residence in the shelters.

Random Sampling A random sample is a sample obtained in such a way that

every element in the population has an equal chance of being selected.

Why is the sampling technique in the previous example not a random sample? Describe an appropriate way to select a random sample of the city’s homeless.

By selecting people from a shelter, homeless people who do not go to the shelters have no change of being selected. An appropriate method would be to randomly select neighborhoods of the city and then randomly survey homeless people within the selected neighborhoods.

Graphic Data RepresentationHistogram

Bar Chart

Pie Chart

Frequency distribution graph

Categorical data graph

Categorical data graph %

Stem and leaf plot

The table below shows the number of hours students watch TV in one week. Make a histogram of all the data.

Number of hours of TV

1 II 6 III

2 IIII 7 IIII IIII

3 IIII IIII 8 III

4 IIII I 9 IIII

5 IIII III

Step 1: Make a frequency table of the data. Be sure to use equal intervals.

Number of hours of TV

Frequency

1-3 15

4-6 17

7-9 16

Number of Number of hours of TVhours of TV

FrequencyFrequency

1-31-3 1515

4-64-6 1717

7-97-9 1616

Step 2: Choose an appropriate scale and interval for the vertical axis. The greatest value on the scale should be at least as great as the greatest frequency.

0

4

8

12

16

20

1-3 4-6 7-9

Step 3: Draw a bar for each interval. The height of the bar is the frequency for that interval. Bars must touch but not overlap.Label the axes and give the graph title

Hours of Television Watched

0

4

8

12

16

20

1-3 4-6 7-9

Hours

Nu

mb

er

of

stu

de

nts

Pie graphs

Below are the College Algebra student Sequences test results for the sequences test that we took last week. Construct a pie chart to represent the data.  Test grade Frequency

A 15B 11C 1D 1F 0