A biopsychologist is interested in how quickly rats learn a complicated maze.He puts 5 rats,labeled A,B,C,D,and E,in a box.He wants to run two of the rats through a maze,one rat at a time.How many subsets of 2 rats could he choose to run through the maze if order does matter?
A)6
B)10
C)20
D)120

Question

Quizplus · Accepted Answer

When order matters, we use permutations. The number of ways to choose 2 rats from 5 is given by 5P2 = 5! / (5-2)! = 20.

A Biopsychologist Is Interested in How Quickly Rats Learn a Complicated