Question

According to the October 2003 Current Population Survey, the following table summarizes probabilities for randomly selecting a full-time student in various age groups:
Age
15–17 .009
18–24 .623
25–34 .210
35 or older
Probability .158

Reference: Ref 9-3

If we randomly select a full-time student, the probability that he/she is not 18-24 years old is
A. .377.
B. .623.
C. .75.
D. 1.

Answer 1

Since all the probabilities = 1, we just need to add up the other 3? = A

Answer 2

@CliffSedge

Answer 3

Or subtract 0.623 from 1, yes.

Answer 4

Subtraction rule for complements.

Answer 5

Yeah that too :P.