Number of Non-Fiction Humourous Books for Children in a Bookstore

[kerrwilk]

Homework Statement

There are 54 books in a book store: 28 are fiction, 21 are humour and 17 are children’s books. If 12 of the books are humourous fiction, 8 are children’s fiction, 3 are humourous fiction for children and 10 are serious non-fiction for adults, how many books are non-fiction humour for children.

Homework Equations

n(total) = n(C) + n(F) + n(H) – n(C + F) – n(C + H) – n(F + H) + n(F + C + H)

The Attempt at a Solution

Let x= the number of non-fiction humour for children.

n(total) = n(C) + n(F) + n(H) – n(C + F) – n(C + H) – n(F + H) + n(F + C + H)
44 = (9-x+5+3+x) + (11+9+3+5) + (9+3+x+9-x) – (5+3) – (3+x) – (3+9) + 3
44 = 46 –x
-2 = -x
x=2

I am a bit confused by the wording. Does "28 are fiction" mean that there are 28 books that are only fiction (and nothing else) or does it mean there are 28 fictional books including the humourous fiction and children’s fiction? I took it to mean the latter. Did I do this correctly? Thanks for your help.

My Diagram is attached.

 

[armolinasf]

I think you're correct in saying that there are 28 fictional books including the humorous fiction and children's fiction since if there were 28 purely fictional stories that were nothing else you have to have more than 54 total books.

 

[zgozvrm]

Looks good to me...

That's exactly how I'd solve it.

 

[kerrwilk]

Thanks for your help.