##### Probability that a hash table using chaining for collision resolution has a chain of atleast 3 out of 4 keys.

why option c is wrong becoz making of atleast 3 chain size it will probability of 1/8 ?

##### 1Comment
shivani
20 Aug 2017 10:44 am

Since , it is given 4 keys are there , then we can say that chain of size 3 and 4 can be obtained.

• Let us consider chain of size 3, then P(chain is of size 3) = 8C1 * 4C3 *7C1/84 //   8C1 for select ing 1st slot for a chain of length 3 ,4C3  for selecting 3 out of 4 keys to form chain ,7C1  for selecting 2 nd slot for holding 1 key
• Let us consider chain of size 4, then P(chain is of size 4) = 8C1 /84
• P = 8C1 * 4C3 *7C1/84  8C1 /84
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