Step 1: Start with what you know
We need to fill an area with dirt that measures 2 m × 3 m × 5 m. To find the volume, we multiply the three dimensions together:
\(2\:\text{m}\times3\:\text{m}\times5\:\text{m}=30\:\text{m}^{3}\)
So we need \(30\:\text{m}^{3}\) of dirt.
Step 2: Determine what you want to get in the end. (Figure out what the end units should be.) = \(\text{yd}^{3}\)
Step 3: Determine what conversion factor(s) to use. You may sometimes need more than one.
We know that 1 yd = 0.9144 m and we can use this information to find \(\text{yd}^{3}\):
1 yd = 0.9144 m
Cube both sides of the equation:
\(\text{(1 yard)}^{3}\) = \(\text{(0.9144 m)}^{3}\)
Which gives us:
\(1\:\text{yard}^{3}= 0.7646\:\text{m}^{3}\)
Step 4: Multiply by 1 in the form of the conversion factor that cancels out the unwanted units.
We have \(30\:\text{m}^{3}\) so we need to multiply it by \( \frac{1\:\text{yd}^{3}}{0.7646\:\text{m}^{3}}\):
\(\frac{30\:\text{m}^{3}}{1}\times\frac{1\:\text{yd}^{3}}{0.7646\:\text{m}^{3}}\)
Note that we chose the conversion factor that will enable us to cancel out the existing units and change them to the desired units (\(\text{m}^{3}\) is in the top of our original fraction, so we chose the conversion factor with \(\text{m}^{3}\) in the bottom so they will cancel out)
Then cancel out the \(\text{m}^{3}\).
\(\frac{30\:\cancel{\text{m}^{3}}}{1}\times\frac{1\:\text{yd}^{3}}{0.7646\:\cancel{\text{m}^{3}}}\)
Next, multiply straight across:
\(\frac{30\times 1\:\text{yd}^{3}}{1\times0.7646}\)
Which equals:
\(\frac{30\:\text{yd}^{3}}{0.7646}\)
Then divide 30 by 0.7646, which gives us:
\(39.24\:\text{yd}^{3}\)
So we need \(39.24\:\text{yards}^{3}\) of dirt to fill that volume.