Measures of Center
Find the median and mode of the data:
12, 14, 12, 16, 22, 11, 14
Median 14
Mode: 12 & 14
Identify the population and the sample size for the below question. A survey of 1353 American households found that 18% of the households own a computer.
What is population is all American Households. Sample Size: 1353 Statistic
4, 5, 5, 6, 8, 9, 10, 10
What are the 5 key numbers you would use to make the box and whisker plot? (The 5 number summary)
median 7
lower quartile 5
upper quartile 9.5
minimum 4
maximum 10
A survey shows that 30 students out of 50 prefer dogs to cats. If there were 400 students surveyed, how many prefer dogs?
What is 240?
1.A sports writer wants to know which is the most popular college basketball team. Which group of people would give her the least biased answer?
A. every 4th person entering a college dining hall
B. every 4th student at a freshman orientation
C. every 4th person entering a grocery store
What is C
Find the mean: (round to the tenth)
11, 12, 12, 14, 14, 16, 22
14.4
A recent survey of 2625 elementary school children found that 28% of the children could be classified obese. Identify the population and the sample.
Population: Elementary school children
Sample: 2625 elementary school children
30, 32, 34, 35, 35, 35
What is the 5 number summary used to make a box and whisker plot?
median 34.5
lower quartile32
upper quartile 35
minimum 35
maximum 35
In a recent survey asking which student council president candidate they prefer:
Candidate A Candidate B
14 22 Sample 1
24 12 Sample 2
If there are 500 students in the school, how many students would you expect to vote for candidate B based on Sample 1 (round to whole #)?
Based on Sample 2?
What would be the average of the 2 samples?
Sample 1 - 306
Sample 2 - 167
Average: 237 or 236
You are wanting to find out the favorite store at the mall. You survey 50 random people at the mall. Is this survey biased or unbiased?
Unbiased
FInd the range of the data
11, 12, 12, 14, 14, 16, 22
What is 11
A factory supervisor selects 40 hammers at random from those produced that week and tests for strength. What is the population? What is the sample?
Population - rods produced at the factory last week
Sample - 40 random rods
4, 7, 5, 8 11
What is the 5 number summary to make the box and whisker plot?
In order:4 5 7 8 11
median 7
lower quartile 5
upper quartile 8
minimum 4
maximum 11
When trying to determine the number of fish in a pond, they tag 40 fish.
They pull 4 samples of fish to help them determine the number of fish in the pond.
Tagged Fish Untagged Fish
2 8 Sample 1
3 7 Sample 2
4 6 Sample 3
Based on each of the samples, how many fish would you expect to be in the pond?
Sample 1 -160
Sample 2 - 93.3
Sample 3 - 60
You want to know the favorite sport of students at your school. You randomly sample 15 students at a soccer game.
Biased
11, 12, 12, 14, 14, 16, 22
Distances from the mean
3.4, 2.4, 2.4, .4, .4, 1.6, 7.6 = 18.2/7
MAD - 2.6
Administrators at Belleville High School surveyed 30 random seniors to see how they felt about lunch offerings in the school cafeteria. What is the sample and what is the population?
Sample - 30 random seniors
Population - Seniors and Belleville HS.
You and a group of friends survey students at school asking them their favorite candy bars. You each survey 30 students. There are 750 students at the school. Here are the results of the survey:
Twix Milky Way Snickers
12 14 4 you
15 10 5 friend A
11 12 7 Friend B
Based on the survey, how many students would you expect to choose Milky Way as their favorite candy bar based on each of the friends? Combined?
You: 350
Friend A: 250
Friend B: 300
Combined? 300
The principals want to ban cell phones in school starting next school year. They survey 40 random 8th graders.
biased
Two box and whisker plots are made from the following 5 number summaries.
Data Set A: 3, 5, 7, 11, 14
Data Set B: 5, 6, 9, 12, 16
Express the difference in the measures of center as a multiple of the measure of variation. The difference in medians is how many times the IQR?
What is .333
Measure of center are 7 & 9, the difference is 2.
The variation (IQR) is 6
Therefore, 2/6 = .333
To find out how much the average American earns, the IRS randomly samples 1 in every 1000 tax returns.
What is the population?
What is the sample?
Population - All americans
Sample 1 in every 1000 tax returns
Give the five necessary statistics for the data set below and construct a box and whisker plot: 7,14,10,12,5,19,2
in numeric order 2, 5, 7, 10, 12, 14, 19
What is Min: 2
Q1: 65
Median: 10
Q3: 14
Max: 19
You and a group of friends conduct a survey. Based on the survey, each of you estimates the number of students who prefer pizza for lunch. Here are the estimates:
You: 232
Friend A: 302
Friend B: 288
Friend C: 258
Friend D: 198
Describe the center (median)and the variation (range) of these estimates.
Median: 258
Range: 104
You want to find out the favorite soft drink of students at your school. You randomly ask every 10th student who enters the school building in the morning.
Unbiased