Question

A fish tank holds 29 gal of water. Using the density of 1.00 g/mL for water, determine the number of pounds of water in the fish tank.

Answer 1

The problem is giving us the volume, the density and is asking us for the mass. For this we can use the density equation ($density=\frac{mass}{volume}$) so we solve for mass which is our unknown($mass=density*volume$).

We can´t just multiply this two because they are in different units so we solve this first by turning [gal] to [ml] with the equivalence of 1gal=3785.41 ml

$29 gal *\frac{3785.41 ml}{1 gal} = 109776.89 ml$

Now we can multiply:

$mass=1.00\frac{g}{ml}*109776.89 ml=109776.89 g$

The answer is requested in [pounds] so we solve this by turning [g] to [pounds] with the equivalence of 453.592 g =1 pound

$109776.89 g *\frac{1 pound}{453.592 g} = 242.01 pounds$

Answer 2

1. Convert gallons to mL. 1 gal = 3785.4117840007 mL, multiply that by 29 and get 109776.94173602 mL.

2. Since there is one gram per every mL, there are 109776.94173602 g of water in the fish tank.

3. Convert g to pounds. 1 g = 0.0022 pounds. Multiply 109776.94173602 by 0.0022 and end up with about 241.5 pounds of water.