A psychologist thinks that listening to Mozart helps people think. She gives subjects a set of

puzzles, and measures how many they solve in 5 minutes while listening to Mozart. From data

on many people, the psychologist gets this probability model:

puzzles solved: 1 2 3 4

probability: 0.2 0.4 0.3 0.1

The next two questions concern this model.

1. The probability that a subject solves more than one puzzle is

(a) 0.2

(b) 1

(c) 2.3

(d) 0.8

(e) unknown -- not enough information.

2. The expected number of puzzles that a subject solves is

(a) 0.575

(b) 2.3

(c) 1

(d) 2.5

(e) varies from repetition to repetition.