Q. I am planning a barbecue for 150 people. I plan on 50 pounds of potato salad and 50 pounds of slaw, 150 large hot dogs and 150 hamburgers. I have 14 dozen tarts. I need to know how many average tomatoes and onions to buy as condiments for the dogs and hamburgers — is 30 tomatoes and 25 large onions enough? Also how many watermelons would I need to serve 150 — would 10 do it?
A. No chips?

You’ll have plenty of potato salad and slaw. Depending on the mix of adults to kids, you might want to scale up on the hamburgers and down on the hot dogs a little, or just up on the hamburgers. We’d increase the number of tomatoes a bit in either case, but 25 onions, which can be sliced more thinly, are plenty.

Watermelons vary from soccer-ball sized to huge. The large, elongated ones weigh in between 15 and 35 pounds. Assuming you find 25-pound ones, we don’t think you’d need 250 pounds of watermelon, especially since it is not the only dessert item. We think a half-dozen 25-pound watermelons would be enough.