A math class has 4 girls and 4 boys in the seventh grade and 7 girls and 5 boys in the eighth grade. The teacher randomly selects a seventh grader and a

Question

A math class has 4 girls and 4 boys in the seventh grade and 7 girls and 5
boys in the eighth grade. The teacher randomly selects a seventh grader and an eighth grader from the class for a competition. What is the probability that the students she selects are both boys?

Answer 1

Johnny,

 

Probability that the 7th grader is a boy = number of boys/(total kids) = 4/(4+4) = 1/2

 

Probability that the 8th grader is a boy = 5/(5+7) = 5/12

 

Probability that both are boys = 1/2*(5/12) = 5/24 or 20.8%