Question

A science class has 3 girls and
3 boys in the seventh grade and
4 girls and 1 boy 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

Probability that the 7th grader is a boy = number of boys/number of students = 3 / ( 3 + 3 ) = 3 / 6 = 1 / 2


Probability that the 8th grader is a boy = number of boys/number of students = 1 /( 4 + 1 ) = 1 /5


Probability that both are boys = 1 / 2 * ( 1 / 5 ) = 1 / 10 = 0.1 = 10 %

Answer 2

prob (2 boys)
= 2 (3/6)(1/5)
= 1/5

I multiplied by 2 since it could be
boy from grade7 x boy from grade 8
or boy from grade8 x boy from grade 7

Answer 3

a science class has 5 girls and 3 boys in the seventh grader and 2 girls and 6 boys in the eight grader. the teacher randomly selects a seventh grader and a eight grader for a class competition. what is the probability that the students are both boys