Module 6 Mendelian Genetics

Lesson 5 Lab—Calculating Probability

What are the chances of a person winning the Lotto 649 lottery? One chance in ten million? What are the chances of a person being struck by lightning? One chance in two million? If you are more likely to be struck by lightning than winning the lottery, then which should you be more concerned about?

Probability can be defined as a study of the chance that certain events or phenomena will happen. In this lab, you will explore how probabilities with coin tosses can be either linked or not linked. You will then draw connections between the outcomes of coin tosses with the outcomes of genetic crosses.

Problem (Purpose)

The objective of this investigation is to study the probability associated with tossing coins.

Materials

• paper

• a small cup

• pencil

• two coins of the same denomination

• Module 6: Lesson 5 Assignment document that you saved to your computer earlier in this lesson.

Procedure

• Place one coin in the cup. Cover the cup opening with your hand and shake. Then, toss the coin on the table. Repeat ten times. Record the number of heads and the number of tails you got in Table A of your assignment document.

• Using the same procedure, toss one coin fifty times. Record the number of heads and tails in Table B of your assignment document.

• Toss two coins at the same time forty-eight times using the same procedure as before. For each group of eight tosses, record in Table C in your assignment document the number of double heads, one head one tail, and double tails that you get.

• In this exercise, you want to toss three consecutive heads tossing one coin, or, to speed up the process, toss three coins together and attempt to get heads on all three coins on the same toss. Before you start, predict what your chances are of getting heads on all three coins. Now try it, keeping count of the number of attempts made until you get the first set of three heads. Record the number of tosses it took in the Table D of your assignment document.  Try it again and record the number of tosses in the assignment document.

If you have ever had to guess a coin toss, our experience has probably taught you to appreciate the randomness of chance. In general, the more often an event occurs, the closer the actual frequency comes to the predicted frequency. Sometimes you think you know the probability of an event occurring, but to your dismay it doesn’t happen this way! You later discover that you were lacking some key information. Consider the case in the next lesson.