We use the z statistic:
z = (x – u) / s
But first let us calculate the standard deviation s,
sample x and mean u.
s = sqrt (n p q)
s = sqrt (112 * 0.77 * (1 – 0.77))
s = 4.45
x = 0.81 * 112 = 90.72
u = 0.77 * 112 = 86.24
So the z score is:
z = (90.72 – 86.24) / 4.45
z = 1.00
From the standard tables, the P value at z = 1.00 using
right tailed test is:
P = 0.1587 = 15.87%
