Answer: 2.14 %
Step-by-step explanation:
Given : pH measurements of a chemical solutions have
Mean : 
Standard deviation : 
Let X be the pH reading of a randomly selected customer chemical solution.
We assume pH measurements of this solution have a nearly symmetric/bell-curve distribution (i.e. normal distribution).
The z-score for the normal distribution is given by :-

For x = 6.74

For x = 6.76

The p-value =

In percent, 
Hence, the percent of pH measurements reading below 6.74 OR above 6.76 = 2.14%
Based on the given description above, and the number of guests that is expected to arrive in the family dinner, The minimum number of cupcakes that you will need to bring so that everybody could get at least one cupcake is 23. You should have at least 23 cupcakes. Hope this is the answer that you are looking for. Thanks for posting!
The slope is rise over run so it would be -1/3
That would be scary lol but I guess kinda fun ❤️