McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Probabilities of Independent and Dependent Events
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Exercise 32 Page 921

Follow the steps for designing a simulation using a geometric model.

See solution.

Practice makes perfect

We know that Zoe struck out on 10 % of her at bats last season. We want to design and conduct a simulation to estimate the probability that she will strike out at her next at bat this season. First let's review the steps for designing a simulation.

  1. State each possible outcome and the corresponding theoretical probability.
  2. Determine if there are any assumptions.
  3. Choose and describe an appropriate probability model for the situation.
  4. Define a trial for the situation and choose the number of trials to be conducted.

We will follow these steps, conduct the simulation, and report the results.

Designing a Simulation

Since we are interested in the probability that Zoe will strike out, we have two possible outcomes — striking out and not striking out. Based on the given information, we will assume that the theoretical probability that she strikes out is 10 %.
Possible Outcomes Theoretical Probability
Striking out 10 %
Not striking out (100- 10) % or 90 %

To design the experiment we will use a geometric model. We can use a spinner divided into two sectors — each sector representing one of the probabilities. Let's calculate the measure of the central angle of each sector.

Possible Outcomes Measure of the Central Angle
Striking out 10 %* 360^(∘)=36^(∘)
Not striking out 90 %*360^(∘)=324^(∘)

Now we are ready to create our spinner. Each trial — one spin of the spinner — will represent the result of one of Zoe's at bats.

Let's choose the number of trials to be 20. A successful trial in this case is landing on the area that represents striking out.

Conducting and Summarizing Data from a Simulation

Now we can conduct a simulation. To do this let's spin our spinner 20 times.
Let's use a frequency table to present the example results.
Outcome Tally Frequency
Striking out ||| 3
Not striking out ||||| ||||| ||||| || 17
Total - 20

Using the results from the table, we can calculate the experimental probability P that Zoe will strike out at her next at bat. P=3/20=0.15 The experimental probability that Zoe will strike out at her next at bat is 0.15, or 15 %. Therefore, the experimental probability that she will not strike out is 1-0.15=0.85, or 85 %. Finally, we can create a bar graph showing these results.

Keep in mind that this is just one of many simulations we could do.