Answer:
0.3575
Explanation:
A population with a normal distribution has a mean of 104 and a standard deviation of 15. A sample of 30 items is taken from that population. (a) (4 points) What is the probability of the sample mean is not less than 103?
The probability of the sample mean is not less than 103 means the sample mean is equal to 103
We solve using the z score formula
z = (x-μ)/σ/√n
where
x is the raw score = 103
μ is the population mean = 104
σ is the population standard deviation = 15
n is the random number of sample = 30
z = 103 - 104/15/√30
z = -1/2.7386127875
z = -0.36515
Probability value from Z-Table:
P(x≤ 103) = 0.3575
Therefore, the probability of the sample mean is not less than 103 is 0.3575