Desmos Grade 7 - Unit 8 Review

Desmos Grade 7 - Unit 8 Review

Probability and Statistics

Probability

Write the probability of something happening as a fraction. You can then convert to a decimal or percentage, if needed.

Multiple Choice

What is the probability of rolling a 2 on a fair six-sided number cube?

• $\frac{1}{6}$

• $\frac{2}{6}$

• $\frac{3}{6}$

Multiple Choice

You pick a block out of this box without looking. What is the probability of picking a triangle?

• $\frac{4}{8}$

• $\frac{3}{8}$

• $\frac{1}{8}$

• $\frac{3}{5}$

Multiple Choice

You pick a block out of this box without looking. What is the probability of picking red?

•  $\frac{5}{11}$ 

•  $\frac{4}{11}$ 

•  $\frac{2}{11}$ 

•  $\frac{2}{9}$  

Experimental Probability

Remember that even though the probability of flipping heads on a coin is 50%, that doesn't mean it will ALWAYS be exactly half of your experiments.

Open Ended

You use this spinner with four equal sections to help you decide what to eat for breakfast each morning. Your mom tells you that after 100 days, you will have eaten pancakes exactly 25 times.

Do you agree or disagree with her? Explain your thinking.

Multiple Events

When you are running multiple experiments at the same time, it is sometimes easiest to create a list, table, or tree to help visualize all the possibilities.

Multiple Choice

A Nike store is running a special sales event. When you walk in the store you may spin two spinners to decide your deal. One spinner decides how much you save and the other decides what item you can save on.

How many different combinations could you get?

• 20

• 9

• 14

• 24

Multiple Choice

What is the probability that you save money on/get free shoes?

• $\frac{5}{20}$

• $\frac{4}{20}$

• $\frac{1}{20}$

• $\frac{9}{20}$

Multiple Choice

What is the probability that you save $10 on a hat?

• $\frac{5}{20}$

• $\frac{4}{20}$

• $\frac{1}{20}$

• $\frac{9}{20}$

Population

A population is a set of people or things that we want to study.

Multiple Choice

Mrs. Greear wants to see if the students at Jenifer Middle School want to change the amount of time they get for lunch. What is the population for this question?

• Mrs. Greear

• the students at Jenifer Middle School

• lunch

• the cooks

Multiple Choice

Tony wants to find out how the 7th grade students at his school feel about the amount of homework they receive each week. What is the population for this question?

• Tony

• All the students at his school

• All the 7th grade students at his school

• All 7th graders

Sample

A sample is part of a population. Its distribution should resemble the population's distribution.

(If your population is all 7th grade students, then your sample should include all kinds of 7th grade students, not one specific group)

Multiple Choice

The owner of all the McDonald's in the Valley (there are three) wants to know if the workers at her stores are happy with the hours they work.

Which of the following strategies would produce a representative sample?

• Ask 50 random customers at each store throughout a business day.

• Select 12 random employees from each store.

• Ask all the employees from one store.

• Ask the first 8 employees that arrive to work at each store.

Multiple Choice

The McDonald's owner finds that 28 of the 36 employees surveyed are happy with the hours they work.

If McDonald's has 198 employees, how many do you predict are happy with the hours they work?

• 64

• 56

• 150

• 154

Multiple Select

A class of students was surveyed about the amount of time they spend exercising and playing video games. The results are shown in the dot plots.

Select all the true statements.

• All students play video games more than they exercise.

• Students tend to spend more time on video games than exercising.

• The median time spent on video games is higher than the median time spent exercising.

• All students exercise more than they play video games.

Multiple Select

The dot plots show the grades of 21 students in two different subjects.

Select all the true statements.

• The grades in History are more consistent than the grades in Math.

• The grades in both classes are equally consistent.

• The grades in Math are more consistent than the grades in History.

• The mean grade in History is higher than the mean grade in Math

• The mean grade in Math is higher than the mean grade in History.

Multiple Choice

Tony wants to find out how the 7th grade students at his school feel about the amount of homework they receive each week. What is the population for this question?

• Tony

• All the students at his school

• All the 7th grade students at his school

• All 7th graders