Work out the z scores for 51 and 54
z1 = (51 - 57.5) / 6.5 = -1
z2 = (64 - 57.5)/6.5 = 1
from tables of normal distribution this value os 3413 + 3413 = 68.26%
so the answer is c
Based on the graph, f(3) = 5 when x = 3
Df = g - 10
To solve for d, divide both sides by f.
df / f = (g - 10) / f
d = (g - 10) / f
I hope this explains it.
