1. Either Courses

In a class of 450 students, 300 are taking a mathematics course and 260 are taking a science course. If 140 of these students are taking both courses, how many students are not taking either of these courses?
(1) 30 (3) 110
(2) 40 (4) 140

I know there is a formula or equation for "EITHER" questions such as this one.

What is a good formula or equation to use to find the answer?

2. Originally Posted by magentarita
In a class of 450 students, 300 are taking a mathematics course and 260 are taking a science course. If 140 of these students are taking both courses, how many students are not taking either of these courses?
(1) 30 (3) 110
(2) 40 (4) 140

I know there is a formula or equation for "EITHER" questions such as this one.

What is a good formula or equation to use to find the answer?
I'd suggest you draw a Venn diagram. From it, you should see that the number of students studying mathematics or science is 300 + 260 - 140 = 420 ....

3. A + B - (A and B) = (A or B)
Maths + Science - Both = Either
300 + 260 - 140 = 420
So 420 are taking either maths, science or both meaning that there are 30 students which are not taking either maths or science.

4. yes...

Originally Posted by mr fantastic
I'd suggest you draw a Venn diagram. From it, you should see that the number of students studying mathematics or science is 300 + 260 - 140 = 420 ....
Yes, but I know there is an equation given for such questions. I just can't think of it right now. At the end of the equation, there is a G_1 + G_2 to represent the two groups or something like that.

Do you know which equation it is?