C. 14ft
If you add them all up then divide by how many numbers you added together it will give you the mean
10.7
23.7-10=10
that r the maths
Df/dy=(1350-750)/(2010-2000)
df/dy=60
f(y)=750+60(y-2000) or neatened up a bit...
f(y)=60y-119250 (note: y is the actual year, ie 2005, not year like 2 years from start)
