Question

a simple random sample of size 36 is taken from a normal population with mean 20 and standard deivation of 15. What is the probability the sample,neab,xbar based on these 36 observations will be within 4 units of the population mean. round to the hundreths place

Answer 1

Solution :

= / n = 15 / 36 = 2.5

= P[ -4 / 2.5 < ( - ) / < 4 / 2.5)]

= P(-1.6 < Z < 1.6)

= P(Z < 1.6) - P(Z < -1.6)

= 0.8904

Probability = 0.8904