I need to calculate the average Daily price of a particular product within a specified time period i.e. between two dates, Sep 16 2014 & Feb 15 2015

The daily price of the product, during the above-mentioned time period, has revised as per the table below

Aug 31 2014 : $74.58
Oct 01 2014 : $75.46
Oct 15 2014 : $74.29
NOv 01 2014 : $71.68
Dec 01 2014 : $70.73
Dec 16 2014 : $68.65
Jan 12 2015 : $68.66
Jan 17 2015 : $66.64
Feb 04 2015 : $64.60


Thanks for the help

San