Grade 4 - Progress in Mathematics

Update your skills. See page 27.

Events and Outcomes

7-8

The probability of an event is affected by whether the experiment

is conducted with or without replacement.

Rae put these letters into a bag. She picked

a letter at random ten times and replaced

the letter in the bag each time. Then she

graphed her results.

What conclusion can Rae draw about the

probability of picking B on the 11th pick?

Since Rae puts the card back in the bag after

each pick, the contents of the bag do not

change. So, the probability of picking B is

the same for every pick.

The probability of picking B is always 
^13 
.

As the number of possible outcomes changes,

so does the probability of an event.

Ben put these digits into a bag. He picked

a digit at random and did not replaceit in

the bag. He did this for each pick.

What is the probability of Ben picking 0 on

the 3rd pick?

1st Tr y:5 digits in the bag

Probability of picking 0: 1 out of 5; 
^15 


2nd Tr y: 4 digits in the bag

Probability of picking 0: 1 out of 4; 
^14 


3rd Tr y: 3 digits in the bag

Probability of picking 0: 1 out of 3; 
^13 

The probability of Ben picking 0 on the 3rd pick is 1 out of 3, or 
^13 
.

Think

The probability of picking

B on the 1st pick was

1 out of 3, or 
^13 
.

Number of Times Picked

0 1 2 3 4 5 6

Letter

C

B

A

After 10 Picks

Ben’s Picks

Try Digit

1st 8

2nd 6

3rd

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