Answer:

Step-by-step explanation:
Given


Required
Determine the percentage change
Percentage change is calculated as;






<em>Hence, the percentage change is approximately 8.8%</em>
You were right, its the second choice CA=CB+BA
Answer:


And then the percentage between 24 and 40 would be 
Step-by-step explanation:
For this problem we have the following parameters given:

And for this case we want to find the percentage of lightbulb replacement requests numbering between 24 and 40.
From the empirical rule we know that we have 68% of the values within one deviation from the mean, 95% of the values within 2 deviations and 99.7% within 3 deviations.
We can find the number of deviations from themean for the limits with the z score formula we got:

And replacing we got:


And then the percentage between 24 and 40 would be 
-4b-8 + -1b^2 +2b^3
-4(-2)-8+-1(-2)^2+2(-2)^3
8-8+2^2-4^3
4-64
60