Homework 3.3 Addition Rule

The addition rule...

• is used when looking for "and" probability

• takes care of double counting

• is the probability formula that always works

Tags

CCSS.HSS.CP.B.7

Find the probability of being female OR owning a sports car

• $\frac{180}{240}$

• $\frac{84}{240}$

• $\frac{219}{240}$

• $\frac{45}{240}$

Answer explanation

P(A or B) = P(A) + P(B) - P(A and B)

Tags

CCSS.HSS.CP.B.7

What is the probability of buying pizza and a soda?

• $\frac{120}{400}$

• $\frac{182}{400}$

• $\frac{200}{400}$

• $\frac{262}{400}$

Answer explanation

where do pizza and soda meet? $prob\ =\ \frac{number\ desired\ outcomes}{total\ number\ outcomes}$

Tags

CCSS.8.SP.A.4

What is the probability of buying pizza OR a soda?

• $\frac{120}{400}$

• $\frac{182}{400}$

• $\frac{200}{400}$

• $\frac{262}{400}$

Answer explanation

P(A or B) = P(A)+P(B) - P(A and B)

Tags

CCSS.HSS.CP.B.7

How many people own a cat?

• 4

• 6

• 3

• 7

Answer explanation

look at the entire circle!

Tags

CCSS.HSS.CP.A.1

What is the probability someone owns a dog AND cat?

• $\frac{3}{13}$

• $\frac{6}{13}$

• $\frac{10}{13}$
  

• 3

Answer explanation

where do the circles overlap?

$prob\ =\ \frac{number\ desired\ outcomes}{total\ number\ outcomes}$

Tags

CCSS.HSS.CP.A.1

How many people are taking philosophy?

• 18

• 12

• 27

• 30

Answer explanation

whole circle!

Tags

CCSS.HSS.CP.A.1

What is the probability someone is taking philosophy OR sociology?

• $\frac{12}{50}$

• $\frac{41}{50}$

• $\frac{29}{50}$

• $\frac{25}{50}$
  

Answer explanation

P(A or B) = P(A) + p(B) - P(A and B)

Tags

CCSS.HSS.CP.A.1

What is the probability a sutudent ate ice cream or custard?

•  $\frac{9}{107}$ 

•  $\frac{51}{107}$ 

•  $\frac{94}{107}$  

•  $\frac{90}{107}$ 
  

Answer explanation

P(A or B) = P(A) + p(B) - P(A and B)

Tags

CCSS.HSS.CP.A.1

What word tells us to use the addition rule?

• or

• and

• because

• with

Tags

CCSS.HSS.CP.B.7