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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
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 Originally Posted by Country Boy 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
The answer in my book says 2.2 though. Don't know how that's derived.

September 2nd, 2015, 06:13 PM   #4
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Quote:
 Originally Posted by Country Boy 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
1. Your arithmetic is wrong. It adds up to 180, not 189.

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
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 Originally Posted by EvanJ 1. Your arithmetic is wrong. It adds up to 180, not 189. 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.
I found out that you divide 1.8 by .82 (% of listeners) to get 2.2. Thanks guys.

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