Answer:
a. 
b. 
Step-by-step explanation:
First, we need tot find a general expression for the amount of caffeine remaining in the body after certain time. As the problem states that every hour x percent of caffeine leaves the body, we must substract that percentage from the initial quantity of caffeine, by each hour passing. That expression would be:

Then, to find the amount of caffeine metabolized per hour, we need to differentiate the previous equation. Following the differentiation rules we get:

The rate is negative as it represents the amount of caffeine leaving the body at certain time.
Y=5 because you add 4+1=5
Hello here is a solution :
Step-by-step explanation:
normally, if we have the gradient (or slope of inclination or change rate) and a point, we start using the point-slope form :
y - y1 = a(x - x1)
with (x1, y1) being a point on the line, and a being the slope of gradient (or ... however you want to call it).
y - 1 = 2(x - 2) = 2x - 4
y + 3 = 2x
2x - y = 3
<u>Answer- </u>D. There is a strong negative association between the variables
<u>Solution-</u>
Properties of Correlation Coefficient
1- Its value ranges between -1 and 1.
2- The greater the absolute value of correlation coefficient, the stronger is the linear relationship.
3- The weakest linear relationship is indicated by a correlation coefficient equal to 0.
4- A positive correlation means that if one variable gets bigger, the other variable tends to get bigger.
5- A negative correlation means that if one variable gets bigger, the other variable tends to get smaller.
As the given correlation coefficient is -0.98 (-ve), whose absolute value is 0.98 (closer to 1)
So there is a strong negative association between the variables.