The pH measurements of water specimens from various locations along a given river basin are Normally distributed with mean 8 and standard deviation 0.3.
What is the approximate probability that the pH measurement of a randomly selected water specimen is greater than 8.2?

Question

Quizplus · Accepted Answer

We need to find the probability that pH value is greater than 8.2 which can be calculated using z-score formula i.e.
z=(8.2-8)/0.3=2/3
Now, we need to find the area under the standard normal distribution curve to the right of z=2/3 i.e. P(Z>2/3). 
Using a standard normal distribution table, we get P(Z>2/3)=0.2525. 
Therefore, the approximate probability that the pH measurement of a randomly selected water specimen is greater than 8.2 is 0.2525.

The PH Measurements of Water Specimens from Various Locations Along