Difference between revisions of "2005 iTest Problems/Problem 10"

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==Problem==
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The probability of U2 dismantling an atomic bomb is <math>11\%</math>. The probability of Coldplay finding X & Y is <math>23\%</math>. If the probability of both events occurring is <math> 6\%,</math> find the probability that neither occurs.
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==Solution 1==
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By the Principle of Inclusion-Exclusion, the probability of U2 dismantling an atomic bomb and Coldplay NOT finding X & Y is <math>11\%-6\%=5\%</math>. Similarly, the probability of Coldplay finding X & Y and U2 NOT dismantling an atomic bomb is <math>17\%</math>. Therefore, the probability that neither occurs is <math>100\%-5\%-17\%-6\%=\boxed{72\%}</math>.
  
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==See Also==
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{{iTest box|year=2005|num-b=9|num-a=11}}
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[[Category: Introductory Combinatorics Problems]]

Latest revision as of 19:02, 13 October 2025

Problem

The probability of U2 dismantling an atomic bomb is $11\%$. The probability of Coldplay finding X & Y is $23\%$. If the probability of both events occurring is $6\%,$ find the probability that neither occurs.

Solution 1

By the Principle of Inclusion-Exclusion, the probability of U2 dismantling an atomic bomb and Coldplay NOT finding X & Y is $11\%-6\%=5\%$. Similarly, the probability of Coldplay finding X & Y and U2 NOT dismantling an atomic bomb is $17\%$. Therefore, the probability that neither occurs is $100\%-5\%-17\%-6\%=\boxed{72\%}$.

See Also

2005 iTest (Problems, Answer Key)
Preceded by:
Problem 9
Followed by:
Problem 11
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