Answer to Question #29356 in Statistics and Probability for Rudy

Question

A computer is programmed to randomly present stimuli that vary in shape (square and circle). The program is written such that a square is 5 times more likely to appear than a circle. What is the probability that the first figure presented on the screen will be a circle? What is the probability that the first figure presented on the screen will be a square?

Answer 1

Let the probability of a circle appearance be C. Then the probability of a square appearance is S = 5C. The full probability is 1, so

C + S = 1 ==> C + 5C = 1 ==> 6C = 1 ==> c = 1/6.

Therefore, the probability that the first figure presented on the screen will be a circle is C = 1/6 and the probability that the first figure presented on the screen will be a square is S = 5/6.