Grade 4 - Progress in Mathematics

Compute Probability

9-9

There are 10 marbles in the jar:

1 is purple, 2 are white, 3 are red, and

4 are yellow. What is the probability that,

without looking, you would pick a marble

of each color?

The probability that you would pick:


purple is 1 out of 10, or 
 11 
 0.


white is 2 out of 10, or 
 120 
.


red is 3 out of 10, or 
 1

3

0 
.


yellow is 4 out of 10, or 
 1

4


 0.

Probability of picking Write: P(red) 
 1

3

0 


a red marble: 
 1

3

0 

What is the probability that you would

pick a red ora purple marble?

To find the probability of picking red

orpurple, add the two probabilities

by adding the fractions.

Probability of picking red Write: P(red or purple) 
 140 


orpurple: 
 140 

3 red marbles

10 total

marbles

P(red) P(purple)

Find the probability of each event. Use the spinner.

1. P(green) 2. P(yellow)


2. P(blue) 4. P(green or yellow)


3. P(red or blue) 6. P(green or yellow or red) 7. P(red)

 130 

 110 

 140 

Probability

of an event

number of favorable outcomes

number of possible outcomes

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