charity fund raising

there is a limit of 30% for the cost of fund raising for charitable organisations. the nkf had exceeded this amount. others claimed that they were able to keep cost to 30% which is well and good. in the case of a charity fund raising show like those on tv, many of the cost will have to be incurred up front. and then the donations from the public will come in during the show. how could the organisers of such charity shows maintained that they can keep cost down to 30% of fund raised when the cost is a pre show expenditure while the donations is unpredictable and depends on so many variables? an expenditure of $1m must bring in a donation of more than $3.5 mil to keep cost down to 30%. what happens if the donation does not come in? in a charity show, there is no way to guarantee that the cost will be less than 30% unless the organisers can guarantee a minimum sum before the show starts.