SOLUTION: Assume that blood pressure readings have a mean of 120 and a standard deviation of 8. If 100 people are randomly selected, find the probability that their mean blood pressure will

Algebra ->  Probability-and-statistics -> SOLUTION: Assume that blood pressure readings have a mean of 120 and a standard deviation of 8. If 100 people are randomly selected, find the probability that their mean blood pressure will       Log On


   

Question 1086127: Assume that blood pressure readings have a mean of 120 and a standard deviation of 8. If 100 people are randomly selected, find the probability that their mean blood pressure will be greater than 122.

a. 0.8819

b. 0.9938

c. not enough information to determine

d. 0.0062

e. 0.8615
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
This is a z-test since population sd is assumed to be known
z=(x-mean)/s/sqrt(n)
z=(122-120)/8/sqrt(100)
=2*10/8, inverting the denominator and multiplying.
=2.5
Want probability of z>2.5
That is 0.0062
It is much easier for a random BP to be above 122 than it is the mean of 100 of them, coming from a population where the mean is 120.
D.