Question

A math class has 7 girls and 3 boys in the seventh grade and 5 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? Write your answer as a fraction in simplest form.

Answer 1

$|\Omega|=10\cdot10=100\\ |A|=3\cdot5=15\\\\ P(A)=\dfrac{15}{100}=\dfrac{3}{20}$