Reasoning Random Samples

A movie theater randomly samples the types of admission tickets sold on Friday in the afternoon and the evening. If 400 tickets are sold on a Friday afternoon, use your inference and proportional reasoning skills to determine how many of those 400 tickets would be adult tickets. Type your numerical answer only.

Using your inference skills and proportional reasoning, predict the number of purple jellybeans in a bag of 200 total jellybeans if a random sample of 25 resulted in 4 purple jellybeans. I predict there will be _________ purple jellybeans.

A representative sample of 80 customers in a clothing store was surveyed about how they paid for their purchases. The table shows the responses. Based on the results, which of the following are valid inferences. Select all that apply.

• Tomorrow, 8 out of the first 80 customers will for sure pay with a gift card.

• In a group of 40 customers, it is expected that about 10 will pay with cash.

• About 0.3, or 30%, of all the store's customers will pay with a credit card.

• A sample of 100 customers would provide less reliable data.

Yadira wanted to estimate the mean number of words per page in a 180-page book she is reading. Which if these sampling methods gives the best estimate of the mean word count per page in the book?

• Count the words on one randomly chosen page.

• Calculate the mean word count for a sample consisting of the pages with pictures.

• Calculate the mean word count for a sample of 20 pages selected by choosing every 9th page.

• Calculate the mean word count for a sample consisting of the 10 pages that appear to have the most words.

A travel club has 3,000 members. A random sample of 50 of the club members found that 12 people like mountain vacations best. Which statement is NOT supported by the sample data?

• Twenty-four percent of those sampled say they like mountain vacations best.

• An estimated 720 club members would likely say they enjoy mountain vacations best.

• Almost one-quarter of club members would likely say they enjoy mountain vacations best.

• More than 2,500 club members would likely say they prefer other vacations over mountain vacations.

Select all that apply!

• A

• B

• C

• D

• E

• Sample A

• Sample B

• Sample C

The counselors at a camp are scheduling activities for family visitation day. They decide to conduct a survey to determine which activities campers would most like to share with their families. Which describes a method for getting a sample that is both representative and random?

• During the dinner hour, announce that any camper interested in doing so can collect and complete a survey.

• During camp free time, ask every fifth camper in the arts and crafts hall to complete a survey.

• During morning roll call, ask every tenth camper to complete a survey.

• During camp free time, ask all campers down at the lake to complete a survey.

Johanna was running for class president. She wanted to know if she had a good chance of winning the election, so she decided to have her classmates help her with surveys. Michael surveyed a random sample of 10 students from the school. 7 of them said they would vote for Johanna. If there are 230 students in the school, and all of them vote, what is Michael’s best estimate of the number of students who would vote for Johanna? _________ students

An inspector tests 15 random samples of 100 microchips from Hitech Microchips and 15 random samples of 100 microchips from Speedy Microchips. The dot plots show the number of defective microchips in each sample. What is the mean for both Hitech Microchips and Speedy Microchips?

• HM: 5.8

  SM: 6.4

• HM: 5.6

  SM: 6.6

• HM: 5.8

  SM: 6.6

• HM: 6.0

  SM: 6.2