Andy, bette, cate, dustin, erik, and franco are rock collectors. Each collector has chosen some rocks from his ir her collection to trade. Each collector is going to trade with every other collector. How many different pairs of collectors will trade rocks?

Answer: 30 different pairs of collectors will trade rocks

Step-by-step explanation:

Andy, bette, cate, dustin, erik, and franco are six in number

Since each collector is going to trade with every other, the different way of trade will be 6 permutation 2

6P2 = 6! / (6-2) ! = (6*5*4!) / 4! = 6*5 = 30 ways

Therefore 30 different pairs of collectors will trade rocks