Calculating the Probability of Choosing Three Comedies

Oct 13, 2025 by wbrum.org 32 views

When it comes to choosing movies for a vacation, the options can be overwhelming. In this scenario, Christina has a total of 20 movies to select from, consisting of 9 action movies, 7 science fiction movies, and 4 comedies. The task is to determine the probability of Christina randomly choosing three comedies from the given collection.

Calculating the Probability of Choosing Three Comedies

To calculate the probability of choosing three comedies, we need to consider the total number of ways Christina can select three movies from the entire collection and the number of ways she can select three comedies specifically.

The total number of movies is 20, and Christina is choosing 3 movies. This is a combination problem, where the order of selection does not matter. The formula for combinations is given by:

C(n, k) = n! / (k!(n-k)!)

where n is the total number of items, k is the number of items to choose, and ! denotes the factorial function.

In this case, the total number of ways to choose 3 movies from 20 is:

C(20, 3) = 20! / (3!(20-3)!) = 20! / (3!17!) = (20 × 19 × 18) / (3 × 2 × 1) = 1140

Now, let's calculate the number of ways to choose 3 comedies from the 4 available. Using the same combination formula:

C(4, 3) = 4! / (3!(4-3)!) = 4! / (3!1!) = 4

So, there are 4 ways to choose 3 comedies from the 4 available.

Expressing the Probability

The probability of choosing three comedies can be expressed as the ratio of the number of ways to choose 3 comedies to the total number of ways to choose 3 movies:

P(3 comedies) = C(4, 3) / C(20, 3) = 4 / 1140 = 1 / 285

Therefore, the probability that Christina will choose three comedies can be expressed as 1/285.

Conclusion

In the previous section, we explored the probability of Christina choosing three comedies from a collection of 20 movies. Now, let's address some frequently asked questions related to this topic.

Q: What is the total number of movies in the collection?

A: The total number of movies in the collection is 20, consisting of 9 action movies, 7 science fiction movies, and 4 comedies.

Q: How many ways can Christina choose 3 movies from the entire collection?

A: The total number of ways to choose 3 movies from 20 is 1140, calculated using the combination formula C(20, 3).

Q: How many ways can Christina choose 3 comedies from the 4 available?

A: The number of ways to choose 3 comedies from 4 is 4, calculated using the combination formula C(4, 3).

Q: What is the probability of choosing three comedies?

A: The probability of choosing three comedies is 1/285, calculated as the ratio of the number of ways to choose 3 comedies to the total number of ways to choose 3 movies.

Q: Can I use a calculator to calculate the probability?

A: Yes, you can use a calculator to calculate the probability. Simply enter the values into the combination formula and calculate the result.

Q: What if Christina wants to choose 2 comedies instead of 3? How would the probability change?

A: If Christina wants to choose 2 comedies instead of 3, the number of ways to choose 2 comedies from 4 would be C(4, 2) = 6. The total number of ways to choose 2 movies from 20 would be C(20, 2) = 190. The probability of choosing 2 comedies would be 6/190 = 3/95.

Q: Can I apply this probability concept to real-life situations?

A: Yes, the concept of probability can be applied to various real-life situations, such as predicting the outcome of a coin toss, determining the likelihood of a certain event occurring, or analyzing the results of a survey.

Q: What are some common mistakes to avoid when calculating probability?

A: Some common mistakes to avoid when calculating probability include:

Not considering the total number of possible outcomes
Not accounting for the number of favorable outcomes
Not using the correct formula for combinations or permutations
Not double-checking calculations for errors

Q: Can I use software or online tools to calculate probability?

A: Yes, there are various software and online tools available that can help you calculate probability, such as calculators, spreadsheets, or online probability calculators.

Conclusion

In conclusion, the probability of Christina choosing three comedies from a collection of 20 movies can be expressed as 1/285. By understanding the concept of probability and applying it to real-life situations, you can make informed decisions and predictions. Remember to avoid common mistakes when calculating probability and consider using software or online tools to simplify the process.