Taylor S. answered 08/29/19
Patient and Experienced Math tutor
First, since the water’s rate of change is measured in OUNCES per minutes, we must change our gallons to ounces.
1 gallon = 128 oz
5 gallons = (128)(5) oz = 640 oz
First bucket starts with 5 gallons/ 640 oz of water and is leaking out at a rate of 7 oz/minute.
This can be expressed as;
V1 = 640 - 7t
where t = minutes and V1 = volume of water in the first, leaky bucket.
Second bucket starts with 0 gallons/0 oz of water and is gaining water at a rate of 4 oz/minute
This can be expressed as;
V2 = 0 + 4t
where t = minutes again and V2 = volume of water in the second bucket that is gaining water.
Since we want the two volumes of water to be the same, we can set up the following equation;
V1 = V2
Then, substitute
640 - 7t = 0 + 4t
Solve for t
640 - 7t = 4t
+7t +7t
640 = 11t
640 = 11t
11 11
640 = t
11
t ~ 58.18
So, since t represents minutes, it will take 58.18 minutes for each bucket to have the same volume.
To find that volume, plug 58.18 or 640/11 into either equation (since the volumes will be the same).
(Note: I personally plug in the fraction since it is more precise.)
V2 = 4(640/11)
= 2560/11 oz
~ 232.73 oz
So, we found that after about 58.18 minutes, the two buckets will have the same volume of 232.73 OUNCES.
However, the question asks for the answer in gallons so we must convert it back.
To do this, we can set up the ratio;
1 gallon = 128 oz
X gallons 232.73 oz
Cross multiply to get;
232.73 = 128x
232.73 = 128x
128 128
x ~ 1.82 gallons
Finally, we found that after about 58.18 minutes, the two buckets will have the same volume of about 1.82 gallons.