A school choir has 80 students; 36 of them are in seventh grade. Also, 40 students in the choir are girls; 18 of them are in seventh grade. What is the probability that a student picked at random from the choir is either a girl or is in seventh grade?
Probability is favorable outcome to total possibilities.
So, any probability will be x/80
There are 36 seventh graders, and 22 girls in eighth grade (40-18=22). 36+22=58
The probability of drawing either a seventh grader or a girl is 58/80, or 72.5%