Answer
(a) The depth of the water is determined by the amount of time after water begins to fill the vase. So the dependent variable $d$ can be expressed as a function of the independent variable $t$.
(b) Domain: $[0,5]$
Range: $[0,30]$
(c) See graph
(d) $d(4) \approx 27$
This means that the depth of the water is 27 cm after 4 seconds
Work Step by Step
(a) For every $t$ value there is one $d$ value, so $d$ is a function of $t$
(b) Since the vase is being filled from 0 to 5 seconds, it makes sense that the domain is from 0 to 5.
(c) Since the depth of the water cannot go below 0 or exceed 30 cm, the range is 0 to 30.
(d) By looking at the graph, we can estimate $d(4)$ which is the depth after 4 seconds.
