Well really they should have asked how many full servings will there be and is there any left fro the host or something. You might want to explain the "simplest solution is most likely correct" criteria but it does seem silly as she clearly understands.
A point on majority culture - in some schools it is how many generations have attended, in some wealth, in some race, in some religion. There always is a majority culture and an outsider needs to get an in somehow.
Also if a school is government funded (as in the example another poster listed) then a reasonable person would accept a trasparent system with the tours/open days publically advertised and held and therefore may not think to ring up to book a tour a year in advance - this doesn't mean they don't care, just they don't have a contact in "the know".
