SOLUTION: According to the WHO MONICA Project the mean blood pressure for people in China is 128 mmHg with a standard deviation of 23 mmHg (Kuulasmaa, Hense & Tolonen, 1998). Blood pressure

Algebra ->  Statistics  -> Density-curves-and-normal-distributions -> SOLUTION: According to the WHO MONICA Project the mean blood pressure for people in China is 128 mmHg with a standard deviation of 23 mmHg (Kuulasmaa, Hense & Tolonen, 1998). Blood pressure      Log On


   

Question 1186330: According to the WHO MONICA Project the mean blood pressure for people in China is 128 mmHg with a standard deviation of 23 mmHg (Kuulasmaa, Hense & Tolonen, 1998). Blood pressure is normally distributed.
a.) State the random variable.
b.) Suppose a sample of size 15 is taken. State the shape of the distribution of the sample mean.
c.) Suppose a sample of size 15 is taken. State the mean of the sample mean.
d.) Suppose a sample of size 15 is taken. State the standard deviation of the sample mean.
e.) Suppose a sample of size 15 is taken. Find the probability that the sample mean blood pressure is more than 135 mmHg.
f.) Would it be unusual to find a sample mean of 15 people in China of more than 135 mmHg? Why or why not?
g.) If you did find a sample mean for 15 people in China to be more than 135 mmHg, what might you conclude?

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
random variable is the blood pressure.
n=15 from a normal distribution is normally distributed itself with sample mean (for n=15) 128, same as pop. mean and sd of 23/sqrt(15) mm
-
z=(xbar-mean)/sigma/sqrt(n)
=(135-128)*sqrt(135)/23
=1.18
probability of that z or greater is 0.1190
It would not be common but not unusual to find that value.
If I found a value >135, what I would think of it would depend upon what my cutoff value for abnormal were, before I did the study. Since most cutoff values are <0.10, I would likely not consider the value abnormal.