Difference between revisions of "2011 AMC 12B Problems/Problem 9"
(→Solution) |
|||
Line 15: | Line 15: | ||
{{AMC12 box|year=2011|ab=B|num-b=8|num-a=10}} | {{AMC12 box|year=2011|ab=B|num-b=8|num-a=10}} | ||
+ | {{MAA Notice}} |
Latest revision as of 10:03, 4 July 2013
Problem
Two real numbers are selected independently and at random from the interval . What is the probability that the product of those numbers is greater than zero?
Solution
For the product to be greater than zero, we must have either both numbers negative or both positive.
Both numbers are negative with a chance.
Both numbers are positive with a chance.
Therefore, the total probability is and we are done.
2011 AMC 12B (Problems • Answer Key • Resources) | |
Preceded by Problem 8 |
Followed by Problem 10 |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | |
All AMC 12 Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.