A = {students under 15 years old}
B = {Secondary 2 students}

n (A n B’) = 5

Now, what this means is this.

Number of students who {A n B’} is 5.

A means students under 15 years old.
B means Secondary 2 students, so B’ means not Secondary 2 students.

n means intersect, or common.

So n (A n B’) = 5 means number of students who are under 15 years old but not a secondary 2 student is 5.

The statement C = {...} is irrelevant to this question.

The question is probably modified but the given solution has not been modified.

for this qn , how would u draw the venn diagram ? it could be that B and C are subsets of A

There are many possible cases here.

It could well be the case that B and C are subsets of A, since Secondary 2 students are likely under 15 years old.

But you never know, there may be a “repeat Secondary 2” student who exceeds 15 years old.

If B and C are subsets of A, you would be drawing circle B and circle C entirely inside circle A which in turn is entirely inside epsilon. Note that B and C have to intersect each other because there is that possibility that a non-Secondary 2 student enters that competition.

To visualise this, think of a fried egg. The egg yolk is entirely inside the egg white.

The correct notation for the answer given in ii) would be :

n｛A' ∩ C｝= 5

B and C may intersect each other as there are likely to be sec 2s who participated in the competition

thanks all

The safest Venn diagram would be the one where each event intersects the other two. This is assuming that the info in i) and ii) are hypothetical situations and not actual. If they are actual then i and ii are linked