2 points on the best fit line are (1.5, 2.5) and (9.5, 20)
from these 2 points
gradient,m = (20- 2.5)/(9.5 - 1.5)
m = 2.19
using y = mx +c for any of the 2 points
...c = -0.78
thus solving for y at x = 11...the best answer is 23.5
