Most "official" U.S. sources will tell you that a serving size of pasta for a single adult is 1/2 cup (4 oz.) So, your 1.5 pounds would serve 6 people, according to those sources (USDA, American Diabetes Association, etc.)
The true answer to your question is that it will depend upon the appetites of those you are feeding and the amount of other dishes you serve along with the pasta.
For a main course serving of pasta, you'll need about 1/2 pound of pasta per person. Therefore, for 70 people, you'll need approximately 35 pounds of pasta.
I would make about 75-80 pounds
25 pounds
50 pounds, a pound per person
A good amount of pasta salad for 40 people would be 5 pounds total... just had a party for 40 people and that's what we had, and there was just a bit left over
8.25
Loads.
For a side dish I'd say about 8
Almost impossible to answer if you don't tell us what else they are having in this meal.
Small bowtie pasta is about 65-68 grams per cup.
i saw on another question it said 1 pound feeds about 4 people assuming the pasta is the main course. so for 30 people, to be safe, i would buy/use 8 pounds of pasta. maybe 7 if you know some people don't eat a lot
20 pounds of shredded chicken will serve approximately 60 people. The amount of chicken needed is very much dependent upon how it is served.