CPhill

The diagonal length is given by

d = √(s^2 + s^2)  =  √(2s^2) = √2s = s√2     where s is the side length

Therefore

s√2 = 15√2 

So, s must equal 15 cm.

Be careful, here...

-8^2  = (-1)*8*8 = (-1)*64 =  -64  ...  but

(-8)^2  = (-8)*(-8)   = 64

The moral of the story is that parentheses do matter....

Rampager1998 has calculated the mean (average)...the problem asked for the median (the "middle" value)....which is the procedure I have described....

Therefore...you have two good statistical measures of the data....!!!

To find the median, arrange the values from lowest to highest.

Since we have even number of values, add the middle two (the 7th and 8th) and divide by 2.

This answer is the median.

The answer is given by :

[ The amount of material ]  / [The  number of pillows made ]  =   16 / 12  = 4 /3 = ( 1 + 1/3 ) yds per pillow

So the answer lies between the integers 1 and 2

Yep...after reading the question again, I believe Melody's answer is the correct one......disregard mine....it would only be correct if we were talking about all the occurences...not just the green ones....