Can some one please help me with these time/volume questions (there easyish)??? Thanx?

Question

The water in a container is being drained out at a constant rate. Five minutes after the water begins to drain, there are 20 litres of water left in the container. Three minutes later there are only 14 litres left in the container.

a. choose the

appropriate word to complete the statements.

In this situation, { time / volume } depends on { time / volume }. Time is the { independent / dependent } variable. Volume is the { independent / dependent } variable.

b. Model this situation by determining an equation that relates V and t, where V is the remaining volume (L) and t is the time (minutes) after the draining starts.

c. Use your model to determine the original amount of water in the container, (that is, the volume when t = 0).

d. If the water started draining out at 9 a.m., at what time will the container be empty?

Answer 1

a.

In this situation, the volume depends on time. Time is the independent variable. Volume is the dependent variable.

b.

From the statements in the question:

At t1=5 min, V1=20 L

At t2=8 min, V2=14 L ==>

The equation that relates V and t is:

V-V1=[(V2-V1)/(t2-t1)]*(t-t1)

V=V1+[(V2-V1)/(t2-t1)]*(t-t1)

V=20+[(14-20)/(8-5)]*(t-5)

V=20-2(t-5)

V=-2t+30

c.

t=0 ==> V=30 L is the original amount of water in the container

d.

V=0 ==> 0=-2t+30 ==> 2t=30 ==> t=15 min

The container will be empty at 9:15 a.m.