1. ## Random Variables/Distributions help

I have no idea how to do the following question, any help is appreciated.

Among healthy adults the concentration of arsenic in the blood is normally distributed with a mean of 3.2 micrograms per decilitre (μg/dL) and a standard deviation of 1.5 μg/dL. Suspecting that groundwater in the local area might be contaminated with arsenic, a resident had her own blood sampled and the arsenic level in her blood was found to be 6.5 μg/dL. Is it reasonable for her to think that she had been exposed to arsenic contamination?

2. Originally Posted by mightysparks
I have no idea how to do the following question, any help is appreciated.

Among healthy adults the concentration of arsenic in the blood is normally distributed with a mean of 3.2 micrograms per decilitre (μg/dL) and a standard deviation of 1.5 μg/dL. Suspecting that groundwater in the local area might be contaminated with arsenic, a resident had her own blood sampled and the arsenic level in her blood was found to be 6.5 μg/dL. Is it reasonable for her to think that she had been exposed to arsenic contamination?
You need to consider Pr(X > 6.5) given X ~ Normal(3.2, 1.5^2) and draw a conclusion.