Theory question 107
ProbabilityThere are 8 boys and 6 girls in a class. If two students are selected at random from the class, find the probability that they are of: (a) The same sex; (b) Different sexes.
Show the model answer
Model answer
(a) (8/14)(7/13) + (6/14)(5/13) = (56 + 30)/182 = 43/91.
(b) 1 − 43/91 = 48/91.
Explanation
Selecting two without replacement: the second draw is out of 13.