My daughter is graduating this May so we are having an open house. She wants a taco bar, queso and bean dip with chips, and a fruit salad. It sounds easy enough to me, but I have no idea how much food to make! She is sending out 49 invitations that would equal 118 people if they all showed up.... PLUS.. she is inviting the rest of her class (37 more) and some of her friends that are juniors (probably about 20 more). With a possibility of about 175 people, I am only absolutely certain of the attendance of 58 of them. I have found information about the quantity of food that will serve "this many" people, but how do I plan it when i have no idea how many in addition to the 58 will show up. We did not request RSVP because it is an open house instead of a party and we did not mention in the invitation that food would be served although it has been spread by word of mouth and it is customary in my area for food to be available at graduation open houses. Thanks in advance!