What is linear probing?

Consider a hash function f defined as f (key) = key mod 13. Suppose I've used linear probing to insert keys 55, 58, 68, 91, 27, 145 in a hash table.
What will be the location of 79 ?

Okay, I get you have some serious homework right now, but you can't expect us to just answer all of them for you. Does this course have TA/Office hours? Talk to your TA or Prof. They should be able to help you out better.

Also Google is your friend with questions like this. Linear Probing Hash Table, this search will answer your question. (BTW there is a 79 in your list.)