Random Sammples
Determine whether the following is random or biased:
Paula wants to know the favorite type of music of students in her class. She puts the names of all of the students in her class in a hat and draws 8 names to survey.
Random
Find the mode of the dot plot on slide 5.
7
If a data set has a higher range is the variability going to be higher or lower.
Higher Variability
A random sample of 10 students at Odyssey Middle School finds that 2 of them will be trying out for the soccer team. If there are 2,000 students at the school how many total students should you predict will try out for the team?
40 students
Determine whether the following is random or biased:
Tina wants to know how many people in her apartment building use the apartments pool. She asks 10 people who are out walking their dogs.
Biased
Find the median of the dot plot on slide 5.
6
See slide 8
Group B
Jerry randomly selects 20 boxes of crayons from the shelf and finds 2 boxes with at least one broken crayon. If the shelf holds 130 boxes, how many would you expect to have at least one broken crayon?
13 boxes
Determine whether the following is random or biased:
Roberto wants to know the favorite sport of adults in his hometown. He asks 50 random people at the park.
Biased
Find the mean of the data on the dot plot on slide 4.
(round to the nearest hundredth)
8.18
see slide 9
Store A
Part of the population of 4,500 elk at a wildlife preserve is infected with a parasite. A random sample of 50 elk shows that 8 of them are infected. How many elk are likely to be infected?
720 elk
Malorie wants to determine the most popular television show amongst teachers at her middle school. She is not able to survey everyone, so she puts the names of each teacher in a hat. Without looking she pulls the names of 10 teachers from a hat and surveys their first period. Will this produce a random sample.
Yes, every class has the same chance of being surveyed.
See slide 3
Softball players are generally shorter than field hockey players.
See slide 7
4th grade
Ms. Robinson selects 10 random tests from the pile of 130 on her desk. The 10 tests have the following grades:
85, 90, 60, 72, 100, 45, 80, 65, 80, 77
How many students should she predict will earn a 70 or higher out of all of the tests?
91 students
A nationwide furniture company wants to survey their customers to determine whether or not they are providing quality customer service across the United States. They have 140 stores with an average of about 3,000 customers each per month. Which sample should the company use to arrive at the most reliable conclusion.
1) 90 customers from one store
2) 90 customers from stores on the west coast
3) 90 customers from the best performing stores
4) 90 customers from each store
4) 90 customers from each store
See Slide 2
2 inches
See slide 6.
3rd Grade
A factory making gaming systems selects 100 random gaming systems to check for defects. It finds that 3 of them had defects and had to be discarded. How many of the gaming systems out of 1,500 should the factory predict will have defects?
45 gaming systems