Stats question , have work and answer shown

[deaky220]

Homework Statement

i didnt know which forum stats is posted in so i posted it here, but the problem says the q is , Sheilas measure glucose level one hour after a sugary drink varies according to the normal distribution (u= 125 mg/dl) and r=10 mg/dl. What is the level L such that there is a probability only 0.05 that the mean glucose level of 4 test results falls above L?

Homework Equations

x= u(mew) + z*r

The Attempt at a Solution

I did a backwards normal calculation of x= 125 + .5199 (from table A probs) * 10 = 130.199

i think its right but i dunno, does the 4 play a part in my equation or is this the wrong way to do it? ANY information would be helpful

 

[HallsofIvy]

Yes, it does. The average of n samples from a population with mean $mu$ and standard deviation $\sigma$ is normally distributed with mean $mu$ and standard deviation $\sigma\sqrt{n}$. Notice that means that the larger sample you have the smaller its standard deviation is and the more "accurate" it is.

 

[Architeuthis Dux]

Hello,

Thank you for reaching out for assistance with your statistics problem. It appears that you have correctly calculated the level L, which is the mean glucose level that has a probability of 0.05 of falling above it. Your equation x= u(mew) + z*r is the correct formula for finding the value of x, which in this case represents the mean glucose level.

To answer your question about the 4, it does not play a direct role in your equation. However, it is important to note that the problem is asking for the mean glucose level of 4 test results, so the value of L that you calculated represents the mean of those 4 results.

I hope this information is helpful. If you have any further questions or concerns, please let me know. Good luck with your studies!