Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
3. Compound Events
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Exercise 21 Page 305

We are given an experiment and want to represent the sample space by making a table. Then we want to find the probability P(1and heads). The sample space of an experiment is the set of all possible outcomes. In this case, the sample space is the result of two stages.

  • Spinning a Spinner — 1, 2,3,4, or 5
  • Flipping a Coin — heads or tails
Keep in mind that there are several ways to make a table. The part that matters most is that the sample space ends up with all of the possible combinations. To make the table, we will list the outcomes of the first exercise in the first row and the outcomes of the second exercise in the left column.
Outcomes 1 2 3 4 5
Heads
Tails

Now we will pair each possible outcome from the first exercise with the possible outcomes from the second exercise.

Outcomes 1 2 3 4 5
Heads 1H 2H 3H 4H 5H
Tails 1T 2T 3T 4T 5T

Finally, we can find P(1 and heads). We can see that there are 10 total outcomes in the sample space and only 1 of them is favorable.

Outcomes 1 2 3 4 5
Heads 1H 2H 3H 4H 5H
Tails 1T 2T 3T 4T 5T
We will use the Probability Formula to find the probability that P(1 and heads) occurs.
P=Favorable Outcomes/Possible Outcomes
P(1 and heads)=1/10
P(1 and heads)=0.1
P(1 and heads)= 10 %
The probability of rolling a 1 and flipping heads is 110, or 10 %.