Question

In a spreadsheet, before entering any data values, first enter "mean =" into cell A2 and the formula "+AVERAGE(A1:J1)" into cell B2. Next, enter "MAD =" into Cell A3 and the formula "=AVEDEV(A1:J1) into cell B3. You should see "#DIV/0 in Cell B2 and "#NUM!" in cell B3. Now enter "1" into cell A1. What do you get for the mean and the MAD of the data set?
Other question:

You are part of a school team planning a charity dog wash. You want to use data from last year's dog wash to predict how long it will take to wash a dog this year.

Last year's dog washing team kept track of how long it took to wash each dog. It took the team 15 minutes, 20 minutes, 10 minutes, 18 minutes, and 25 minutes to wash the dogs that came in the morning. In the afternoon, four more dogs came to get scrubbed clean. It took the team 10 minutes, 12 minutes, 30 minutes, and 13 minutes to wash these dogs.

Find the mean of the washing times and find the mean absolute deviation of the washing times. If necessary, round to the nearest tenth.

The mean is _____
. The mean absolute deviation is approximately ____
minutes.

Answer 1

In the spreadsheet, you get 1 for the mean and 0 for the MAD.

The mean of the dog washing time is 17, and the MAD is 5.5.

To find the mean, add all of the data points together and divide by 9, the number of data points:
15+20+10+18+25+10+12+30+13 = 153/9 = 17

To find the MAD, first find the difference between each data point and the mean; take the absolute value; then average these together.
|15-17|=2
|20-17|=3
|10-17|=7
|18-17|=1
|25-17|=8
|10-17|=7
|12-17|=5
|30-17|=13
|13-17|=4
2+3+7+1+8+7+5+13+4=50/9=5.5