Bidding Statistical Question "Please Help, URGENT"

#1
I have a question that I'm not sure how to answer or what method to go about solving it. The problem looks as follows...

Max Bid | Win Bid
12.41 | 12.07
13.44 | 13.22
13.14| 13.22
13.24 | 13.18
13.40 | 13.07
13.14 | 12.83
etc....

Calculate the 95% certainty range the discount from the max bid. So essentially he wants to know for the overall average, what type of discount range from max bid the winning bid is.

Thank you SOOOOO MUCH