In a college, 30 students are taking a math class and 20 students are taking an English class. 5 students are taking both English and math. How many students are taking either English or math.
take out those five which are taking both, and you are left with 30+20-5=45 students taking either Math or English.
P(MorE)=Pr(M)+Pr(E)-Pr(M+E)
= (30/50)+(20/50)-5/50= 45/50
so if you pick a student at random, you have a probability of .90 of getting a student who is taking Math or English, but not both.
To find out how many students are taking either English or math, we need to add the number of students taking English, the number of students taking math, and then subtract the number of students taking both.
Number of students taking English = 20
Number of students taking math = 30
Number of students taking both English and math = 5
To get the total number of students taking either English or math:
Total = Number of students taking English + Number of students taking math - Number of students taking both
Total = 20 + 30 - 5
Total = 45
Therefore, there are 45 students taking either English or math in the college.