Grade 9 Probability and Statistics Homework Assignment

The last 10 times Jerome tried to access a certain Internet website, he got an error message saying that the site was unavailable. So, he decides the site no longer works and

does not try to access it again.

Is his decision based on theoretical probability, experimental probability, or subjective judgment?

• theoretical probability

• experimental probability

• selective judgement

When Karen’s mother learns she is pregnant, she celebrates by buying a pink baby blanket because she has a feeling the baby will be a girl.

Is her decision based on theoretical probability, experimental probability, or subjective judgment?

• theoretical probability

• experimental probability

• selective judgement

An advertisement for a desktop computer claims it is 80% smaller than other computers. Why did the advertisers decide to include this statistic in the ad?

• small computers. last longer than larger ones.

• the computer can be placed in smaller spaces, leaving room for other things.

• small computers are better for gaming.

Angela visits a website to read reviews about a new MP3 player.

There were three reviews: two people thought it was great, and one person thought it was terrible.

Angela concludes that there is about a 66% chance that she will be happy with the MP3 player. What assumptions did Angela make?

• She assumes the same level of comfort with technology as the reviewers

• She assumes she is interested in the same features as the reviews

• Both are correct.

To discover common fears, Chris asks his classmates if they are frightened by spiders, snakes, rats, or slugs.

What is the problem with data collected in Chris' survey?

• Time: it will take a lot of time for Chris to survey his class

• Use of language: the survey is only limited to 4 choices

• Ethics: Chris may use this information against a classmate in the future

To find out the proportion of people who recycle tin cans, a person counts the number of households with tin cans in their recycling bins.

What is the problem with collecting this data?

• Privacy: The person should not be examining the contents of households’ garbage

• Cost: It will cost a lot of money to conduct this survey

• Bias: the person conducting the survey likes cans too much

Kevin thinks his drama club should spend more money on props. During the intermission of the spring play, he surveys the audience and the cast to see if they agree.

How could the timing of his question influence the responses?

• decisions will based on how good the play was

• decisions will based primarily on what props

  they just saw in the play

• decisions will be based on whether or not people like Kevin

Rena wanted to find out how often people in her neighbourhood used the local bike paths or

walking trails. She asked her neighbours the question: “How much time do you spend outdoors each month?”

How might her neighbours interpret this question?

• people might include time spent in their yard gardening

• people might include time spent walking their dog

• people might include time spent barbecuing on their deck

• All three are possible.

The number of people in your neighbourhood who use public transit at least once a week.

Should a census or sample be used to collect data about this topic?

• census, 100% accuracy is needed

• sample, it would take too long to ask everyone

Should a census or sample be used to collect data about topic below?

The number of hours members of your family spend on the computer in a week.

• sample, surveying one person in your family should give you an accurate idea about every member

• census, its easy to ask everyone in your family