Ambiguous maths question

[TickledOnion]

DD is 9. She was doing maths homework about bar charts.
18 children are asked what their favourite farm animal is. The results are: pig 3, duck 4, goat 5, cow 6.
The question is: how many children voted for duck or pig?
I know that the answer is 7 and that you add the duck and pig votes together, but DD can’t understand how that is correct. She argued that the answer is “3 or 4”.
I tried to explain it by imagining she answered the survey with duck. If I asked her “did you vote for duck or pig?” My answer is yes but she says her answer is duck.
Are we both right?

I think my explanation made things worse. It would make more sense if I said “put your hand up if you voted for duck or pig”.

This is where you need a Venn diagram :)
I agree though the or in sentences can often be confusing as I think it's used in speech to mean 'and'

You may both be right from an English pedant point of view.

But you are right from a maths homework point of view.
She needs to get with it and learn to 'read' wordy maths questions otherwise she'll be in for years of pain and not getting marks.

How many children in total voted duck or pig - would have made more sense.
Can she draw circle with crosses for duck voters and pig voters - then how many voted would be them added together.

duck 'and' pig would mean the intersection though, and as they only got one vote each it would be zero.

'or' means either A or B or both (ie the union), unless stated as 'exactly one of A or B'

But in a way it is being used in the same way as and would in the sentence. How many voted duck and (how many voted) pig. So I can see why she's annoyed.

Some of the later questions were similar but included “in total” at the end of the sentence. She thought that was much clearer.

You wouldn't use a Venn diagram to explain this. They're mutually exclusive events.

The question would be better phrased "how many children in total voted for duck or pig?". The putting their hands up suggestion is an excellent way of explaining it too.

I wonder if this is a problem in other languages or just English.