In: Statistics and Probability
Suppose that a population is known to be normally distributed with µ = 317 and σ = 90. If a random sample of size n = 50 is selected, calculate the probability that the sample mean is greater than 300.
Solution :
Given that,
mean =
= 317
standard deviation =
= 90
=
=317
=
/
n = 90 /
50 = 12.73
P( >300 ) = 1 - P(
< 300)
= 1 - P[(
-
) /
< (300-317) /12.73 ]
= 1 - P(z <-1.34 )
Using z table
= 1 - 0.0901
=0.9099