Conditional Probability - Algebra 2


This is a WebQuest on conditional probability for Algebra 2 students.

Some events are "independent", meaning that they are not affected by any other events.

Other events are "dependent", meaning that the probability of them occurring is dependent on some other event.



You will create an educational poster for your peers, explaining how conditional probability can be calculated from data in a contingency table. You will also create a contingency table of the results of a survey and present on your poster whether the events are independent or dependent, and calculate a sample of conditional probabilities. 


1. Find and summarize three more video clips on conditional probability. Hint: Khan Academy have good videos.

2. Look at the following real-world examples of data in contingency tables.

3. Create a quick survey of your fellow students to collect data on two variables:

     a. The students' age/grade/dominant hand/elementary school attended/any other identifying characteristic.
     b. Their preference for something, e.g. school subjects, sport, or their perceived happiness or stress level.

4. Complete a contingency table for the results of your survey.


5. Choose two outcomes from your results, e.g. "in 10th grade" and "prefers Math over Languages", and determine:

    a) Whether or not these two outcomes are independent.
    b) If they are not independent, what is the conditional probability of the second outcome, e.g. what is the probability that a student
        prefers Math over Languages given that the student is in the 10th grade.
    Repeat these calculations for two more pairs of outcomes.


6. Create an interesting, eye-catching poster containing:

    a) An explanation of the formula for conditional probability.
    b) A brief overview of your survey.
    c) The contingency table of your survey results.
    d) A review of the independence and conditional probability of your three chosen pairs of outcomes.



Rubric for Poster
Criteria Proficient Acceptable Needs Improvement
Eye-catching and informative presentation The poster is easy to read and generates interest from the viewers. Font is large enough to read and neatly arranged. Flow of information is logical. Writing is concise and free of errors. The required information is included on the poster but is not particularly interesting, the font is too small or too large or the writing contains some errors. Poster is difficult to read, it inspires no interest or writing has numerous errors.
Demonstrated understanding of conditional probability Formula is clearly explained in concise, easy to understand language. Formula explanation taken directly from resources.  Formula incorrect and/or not explained.
Correct presentation of data and calculation of results Data from survey correctly presented in contingency table. Independence and conditional probability correctly calculated and presented. Data and calculations mostly presented correctly, with one or two errors or omissions. Numerous errors in the presentation of the data and/or the calculations.
Supplemental documentation Concise, accurate summaries of three chosen video clips. Survey questions and raw data included. Fewer than three video clips summarized or information poorly summarized. Survey questions and/or raw data missing. Very little, or no, supplemental documentation submitted with poster. 



Upon completion of this WebQuest, you should be able to:

  1. Communicate dependency of one event to another in calculating its probability. 

  2. Create and interpret contingency tables based on real-world contexts.  

  3. Determine if conditional probability exists in real-world context examples. 

  4. Create a viable argument as to whether two events are independent or dependent.


Mississippi Common Core Standards:

S-CP.3, S-CP.4, S-CP.5 and S-CP.6




Bazett, T. (2017, November 19). Intro to Conditional Probability. Retrieved from

Mac an Bhaird, C. (2013, April 3). Contingency Tables. Retrieved from