ANSWER:
(b) -77.6 cm/hours
(c) 775 cms
(d) 10 hours
(e) 348 cms
STEP-BY-STEP EXPLANATION:
(b)
We calculate the slope of the line using the following formula:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
We use the two extreme points, like this:
[tex]m=\frac{100-721}{8.7-0.7}=\frac{-621}{8}=-77.6\text{ cm/hours}[/tex]
(c)
We calculate the y-intercept, which would be the height intercept with the slope and the highest point known and closest to time 0, like this:
[tex]\begin{gathered} 721=-77.6\cdot0.7+b \\ \\ b=721+54.32 \\ \\ b\approx775 \end{gathered}[/tex]
(d)
The expected time that the pool is empty is when the height is equal to 0, therefore:
[tex]\begin{gathered} 0=-77.6\cdot \:x+775 \\ \\ x=\frac{-775}{-77.6} \\ \\ x\approx10\text{ hours} \end{gathered}[/tex]
(e)
Now, to determine the height at 5.5 hours, we perform the following equation obtained:
[tex]\begin{gathered} h=-77.6\cdot(5.5)+775 \\ \\ h=-426.8+775 \\ \\ h\approx348\text{ cms} \end{gathered}[/tex]