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SakuRERE

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Misplaced Homework Thread moved from the technical forums

**TL;DR Summary:**Finding the probability with one measurement and multiple measurements on separate days.

Question: Hypokalemia is diagnosed when blood potassium levels are low, below 3.5 mmol/L. Let’s assume we know a patient whose measured potassium levels vary daily according to N(µ = 3.8 mmol/L, σ = 0.2 mmol/L).

**(a) If a single potassium measurement is made, what is the probability that the patient is diagnosed as hypokalemic?**

(b) If measurements are made instead on 4 separate days, what is the probability that the patient is diagnosed with hypokalemia?

For part A -->

(b) If measurements are made instead on 4 separate days, what is the probability that the patient is diagnosed with hypokalemia?

For part A -->

I solved the question as a standardized normal distribution. I tried to find P(x<=3.5),

using the standard normal formula z= X-Mean/SD I converted the X value 3.5 to a Z score and got P(x<=-1.5)

after that, I used the Gauss table to find the probability and it was P(x<=-1.5)= 0.0668

this answer was similar to the answer key provided by our professor.

However, for the second part, the answer key has to be 0.0013 but I can't think of a way to figure it out. And I don't understand how taking different measurements on separate days will influence my probability.

I will appreciate your help, thank you!

I attached the positive and negative Gauss tables for easier accessibility.