Answer: 15.7 meters
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Work Shown:
s = sum of the heights of buildings A,B,C
s/3 = mean of the heights of buildings A,B,C
s/3 = 14.2
s = 3*14.2
s = 42.6
The buildings A,B,C have their heights add up to 42.6
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r = sum of the heights of buildings A,B,C,D,E
r/5 = mean of the heights of buildings A,B,C,D,E
r/5 = 14.8
r = 5*14.8
r = 74
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r-s = (sum of heights of A,B,C,D,E)-(sum of heights of A,B,C)
r-s = sum of the heights of buildings D and E
r-s = 74-42.6
r-s = 31.4
(r-s)/2 = mean height of buildings D and E
(r-s)/2 = 31.4/2
(r-s)/2 = 15.7 meters is the average height of buildings D and E.