Question

"a random sample of size 36 is drawn from a population with a mean of 278. If 86% of the time the sample mean is less than 280, what is the population"

Answer 1

z = invNorm(.86) = (280-278)/(sd/√36)
1.0803 = 2/(sd/6)
(sd/6)(1.0803) = 3
sd = 18/1.0803 = 16.6620 rounded (use the number of decimal points as directed)

Answer 2

Answer:

from where did 3 came from

Step-by-step explanation: