IXL - Find probabilities using the addition rule (Geometry practice)

After growing tired of squinting while driving, Marcy went shopping for a pair of sunglasses. She tried on glasses with different frames and lenses.

The probability that a pair of sunglasses has aviator frames is 0.7, the probability that it has polarized lenses is 0.3, and the probability that it has aviator frames and polarized lenses is 0.1.

What is the probability that a randomly chosen pair of sunglasses has aviator frames or polarized lenses?

Write your answer as a whole number, decimal, or simplified fraction.

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Learn with an example

question

Frank and his brother are at a store shopping for a beanbag chair for their school's library. The store sells beanbag chairs with different fabrics and types of filling.

The probability that a beanbag chair is made from suede is 0.6, the probability that it is filled with beads is 0.2, and the probability that it is made from suede and is filled with beads is 0.1.

What is the probability that a randomly chosen beanbag chair is made from suede or is filled with beads?

Write your answer as a whole number, decimal, or simplified fraction.

key idea

Addition Rule of Probability

For events

and

the Addition Rule relates

(

C or D

)

and

(

C and D

)

(

C or D

)

(

)

(

)

–

(

C and D

)

This equation can be visualized using a Venn diagram:

(subtract to prevent double-counting)

solution

Let

be the event "the beanbag chair is made from suede" and

be the event "the beanbag chair is filled with beads".

It is given that

(

)

0.6

(

)

0.2

and

(

A and B

)

0.1

Use the Addition Rule to find

(

A or B

)

the probability that a beanbag chair is made from suede or is filled with beads.

(

A or B

)

(

)

(

)

–

(

A and B

)

0.6

0.2

–

0.1

0.7

So,

(

A or B

)

0.7

Looking for more? Try these:

Lesson: Compound probability

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Teacher tools

Work it out

Not feeling ready yet? These can help:

AA.1Theoretical and experimental probability

Lesson: Compound probability

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