Difference between revisions of "2002 AMC 12B Problems/Problem 14"

(Problem)
(Solution 2)
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== Solution 1== 6
 
== Solution 1== 6
  
==Solution 2==
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==Solution 2== 6
Because a pair or circles can intersect at most <math>2</math> times, the first circle can intersect the second at <math>2</math> points, the third can intersect the first two at <math>4</math> points, and the fourth can intersect the first three at <math>6</math> points. This means that our answer is <math>2+4+6=\boxed{\mathrm{(D)}\ 12}.</math>
 
  
 
==Solution 3==
 
==Solution 3==

Revision as of 21:09, 3 June 2021

The following problem is from both the 2002 AMC 12B #14 and 2002 AMC 10B #18, so both problems redirect to this page.

Problem

== Solution 1== 6

==Solution 2== 6

Solution 3

Pick a circle any circle- $4$ ways. Then, pick any other circle- $3$ ways. For each of these circles, there will be $2$ intersections for a total of $4*3*2$ = $24$ intersections. However, we have counted each intersection twice, so we divide for overcounting. Therefore, we reach a total of $\frac{24}{2}=\boxed{12}$, which corresponds to $\text{(D)}$.

See also

2002 AMC 10B (ProblemsAnswer KeyResources)
Preceded by
Problem 17
Followed by
Problem 19
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 10 Problems and Solutions
2002 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 13
Followed by
Problem 15
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

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