McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
Practice Test
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Exercise 21 Page 937

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

See solution.

We are given that this quarter Todd earned As in his classes 45 % of the time. Let's design and conduct a simulation to estimate the probability that Todd will earn an A in his next class. 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 Todd will earn an A, we have two possible outcomes — earning an A and not earning an A. Based on the given information, we will assume that the theoretical probability that Todd will earn an A is 45 %.
Possible Outcomes Theoretical Probability
Earning an A 45 %
Not Earning an A (100- 45) % or 55 %

We will also assume that Todd will take the next class. Since we are asked to use a geometric probability 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
Earning an A 45 %* 360^(∘)=162^(∘)
Not Earning an A 55 %*360^(∘)=198^(∘)
Now we are ready to create our spinner. Each trial — one spin of the spinner — will represent the result of one of Todd's classes.
spinner with two regions
Let's choose the number of trials to be 20. A successful trial in this case is landing on the area that represents earning an A.

Conducting and Summarizing Data from a Simulation

Now we can conduct a simulation. To do this let's spin our spinner 20 times.
spinner with two regions
Let's use a frequency table to present the example results.
Outcome Tally Frequency
Earning an A ||||| ||| 8
Not Earning an A ||||| ||||| || 12
Total - 20

Using the results from the table, we can calculate the experimental probability P that Todd will earn an A. P=8/20=0.4 The experimental probability that Todd will earn an A is 0.4, or 40 %. Therefore, the experimental probability that they will not earn an A is 1-0.4=0.6, or 60 %. Finally, we can create a bar graph showing these results.

Notice that this is only an example solution, as we can think of many other simulations we can design and conduct using the given information.