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September 1st, 2015, 08:53 AM  #1 
Newbie Joined: Feb 2015 From: Far Away Posts: 10 Thanks: 0  Media Planning Math
Based on the exposures to a radio commercial, find the average frequency (average number of times the commercial was heard). Number of Times Heard (Frequency) % of Listeners Reached 0 18 1 31 2 24 3 13 4 8 5 6 
September 1st, 2015, 10:53 AM  #2 
Math Team Joined: Jan 2015 From: Alabama Posts: 3,264 Thanks: 902 
The average is the sum of all the values added together, divided by the total number of values. Here the since you are given the frequency you need something like "3 13s" is 13+ 13+ 13 which is the same as 3(13)= 39. So, given that, add 0(1+ 1(31)+ 2(24)+ 3(13)+ 4(+ 5(6)= 31+ 48+ 39+ 32+ 30= 189. Adding the frequencies, there are 0+ 1+ 2+ 3+ 4+ 5= 15 values to be averaged. The average is 189/15= 12.6

September 1st, 2015, 09:30 PM  #3  
Newbie Joined: Feb 2015 From: Far Away Posts: 10 Thanks: 0  Quote:
 
September 2nd, 2015, 06:13 PM  #4  
Senior Member Joined: Oct 2013 From: New York, USA Posts: 650 Thanks: 86  Quote:
2. Given that nobody heard the commercial more than 5 times, the mean number of times it was heard cannot be 180/15 = 12. You need to divide by 100, the sum of the second column, not the sum of the first column. Therefore I would say the answer is 1.8, and I don't know why a book would say 2.2.  
September 3rd, 2015, 12:15 AM  #5  
Newbie Joined: Feb 2015 From: Far Away Posts: 10 Thanks: 0  Quote:
 

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