Respuesta :
A. we use the z statistic to solve this problem
z = (x – u) / s
We calculate the value of the sample mean u and standard deviation s:
u = $30 * 304 = $9120
s = $21 * 304 = $6384
z = (9,600 – 9120) / 6384
z = 0.075
From the normal tables using right tailed test,
P = 0.47
B. At worst 11% means P = 0.11, so the z value at this is z = -1.23
-1.23 = (x – 9120) / 6384
x = 1267.68