Verified answer

A U B = Either A or B so when drawing the venn diagram would be both circles of A and B joint and both coloured in with the rest of the box empty

A ∩ B = A and B so again when drawing the venn diagram the circles must both overlap eachother and then you only colour in the oval part that is formed inbetween the 2 cicles

see this image

http://farm4.static.flickr.com/3411/3609643715_b58...

for A ∪ B it is the sections called a, b and c for A ∩ B it is just section c

So you've got two circles which represent sets A and B that overlap a little bit. OK, we'll call that overlap section C.

A ∪ B is called the UNION of A and B. You can remember it by noting the symbol is like a U (U for Union). This means the part that's in either A or B or both A and B.

A ∩ B means the part that is in A and in B, called the intersection of A and B. You may recall that intersection generally means where two things meet. In this context, we are talking about where A and B meet.

So, let A represent the people taking physics, and B be the students taking chemistry. A ∪ B is the set of students taking either physics or chemistry.

If there are 12 people taking only physics and 15 people taking only chemistry and 10 people taking both physics and chemistry, then

22 people take physics

25 people take chemistry

The union of A and B is the set of people taking either physics or chem or both. In this case, that would be 12 + 15 + 10 = 37.

Another way to arrive at this calculation is to count the number of people in physics (regardless of whether they take chem) and the number of people in chemistry (regardless of whether they take physics), add them together and subtract the overlap.

22 + 25 - 10 = 37.

The reason for subtracting the intersect is that the intersect is counted twice in the above addition, once in the 22 and once in the 25. We must subtract it once to make the net count accurate.

Given two overlapping circles, A and B, where C is the overlap section:

A ∪ B is the whole area of circles A and B, including section C.

A ∩ B is the overlap section C.

A ∪ B ---> A Union B ---> Combine all the elements of A with B without any repetition.

A ∩ B ---> A Intersection B ---> The resultant contains only the common elements between A and B

A U B means combine all both A and B

A intersect B means common for both A and B(Centre part ie., joined part only)

A ∪ B = all elements in A and B (all of them)

but

A ∩ B = Common elements ONLY