A psychologist thinks that listening to Bach helps people think. She gives subjects a set of puzzles and measures how many they solve in five minutes while listening to Bach. From data on many people, the psychologist gets this probability model:

The probability that a subject solves more than one puzzle is

Question

A psychologist thinks that listening to Bach helps people think. She gives subjects a set of puzzles and measures how many they solve in five minutes while listening to Bach. From data on many people, the psychologist gets this probability model:

The probability that a subject solves more than one puzzle is

Quizplus · Accepted Answer

From the probability model given, we can see that the sum of the probabilities of solving more than one puzzle and solving only one puzzle is 0.8+0.1=0.9. Therefore, the probability of solving more than one puzzle is 0.9-0.7=0.2. So the correct choice is B.

A Psychologist Thinks That Listening to Bach Helps People Think