It has 3 zeros, because its a polynomial of degree 3.
A. 6 + 6 = 12
b. 7 + 8 = 15
c. 0 + 0 = 0
d. 5 + -5 = -10
This question is easier than it seems. If there are 9 consecutive integers with the mean being 16, then 16 must be the median. So just add four on top and four below 16 to give you your range of 9 values, 12-20. 12+13+14+15+16+17+18+19+20=144, 144/9=16. So the mean of the first four numbers is (12+13+14+15)/4= 13.5. If you check, 13.5 is also the median of these four numbers.
