Probability of names and papers!
My friend Jaya teaches at a school. One day she conducted a test for three of her students and when they handed back the test papers, they had forgotten to write their names. Jaya returned the papers to the students at random. The probability that none of the three students will get the right paper is a/b where a and b are co-prime. Find a+b.
The answer is 4.
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1 solution
We can do a simple listing.
1 - 2 - 3 -Condition met
1- 2 - 3 - No
1 - 3 -2 - No
2- 1 - 3 - No
2 -3- 1 - Yes
3 - 1 - 2 -Yes
3 -2- 1 - No
Thus, the probability is 2/6=1/3
Therefore, the answer is 4