Difference between revisions of "2003 AMC 8 Problems/Problem 12"

(Undo revision 80370 by Bz1 (talk))
(Solution)
 
(7 intermediate revisions by 5 users not shown)
Line 1: Line 1:
 
==Problem==
 
==Problem==
When a fair six-sided dice is tossed on a table top, the bottom face cannot be seen. What is the probability that the product of the  faces than can be seen is divisible by <math>6</math>?
+
When a fair six-sided dice is tossed on a table top, the bottom face cannot be seen. What is the probability that the product of the  faces that can be seen is divisible by <math>6</math>?
  
 
<math> \textbf{(A)}\ 1/3\qquad\textbf{(B)}\ 1/2\qquad\textbf{(C)}\ 2/3\qquad\textbf{(D)}\ 5/6\qquad\textbf{(E)}\ 1 </math>
 
<math> \textbf{(A)}\ 1/3\qquad\textbf{(B)}\ 1/2\qquad\textbf{(C)}\ 2/3\qquad\textbf{(D)}\ 5/6\qquad\textbf{(E)}\ 1 </math>
  
 
==Solution==
 
==Solution==
All the possibilities where <math>6</math> is on any of the five sides is always divisible by six, and <math>1 \times 2 \times 3 \times 4 \times 5</math> is divisible by <math>6</math> since <math>2 \times 3 = 6</math>. So, the answer is <math>\boxed{\textbf{(E)}\ 1}</math> because the outcome is always divisible by <math>6</math>.
+
We have six cases: each different case, every one where a different number cannot be seen. The rolls that omit numbers one through five are all something times six: an example would be where the number you cannot see is one, so the product should be 2 x 3 x 4 x 5 x 6, and so product should be divisible by six. The roll that omits six on the other hand is 1 x 2 x 3 x 4 x 5, which has 2 x 3, also equal to six. We can see that all of them have a factor of 6 and therefore are divisible by six, so the solution should be E,1.
 
 
==See Also==
 
 
{{AMC8 box|year=2003|num-b=11|num-a=13}}
 
{{AMC8 box|year=2003|num-b=11|num-a=13}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Latest revision as of 13:41, 19 February 2024

Problem

When a fair six-sided dice is tossed on a table top, the bottom face cannot be seen. What is the probability that the product of the faces that can be seen is divisible by $6$?

$\textbf{(A)}\ 1/3\qquad\textbf{(B)}\ 1/2\qquad\textbf{(C)}\ 2/3\qquad\textbf{(D)}\ 5/6\qquad\textbf{(E)}\ 1$

Solution

We have six cases: each different case, every one where a different number cannot be seen. The rolls that omit numbers one through five are all something times six: an example would be where the number you cannot see is one, so the product should be 2 x 3 x 4 x 5 x 6, and so product should be divisible by six. The roll that omits six on the other hand is 1 x 2 x 3 x 4 x 5, which has 2 x 3, also equal to six. We can see that all of them have a factor of 6 and therefore are divisible by six, so the solution should be E,1.

2003 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 11
Followed by
Problem 13
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 AJHSME/AMC 8 Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png