To find the width of the box, we can use the formula for the volume of a right rectangular prism, which is:
\[ \text{Volume} = \text{Length} \times \text{Width} \times \text{Height} \]
We know the volume \(V\) is 162,000 cm³, the height \(h\) is 40 cm, and the length \(l\) is 90 cm. We want to find the width \(w\).
Substituting the known values into the volume formula, we have:
\[ 162,000 = 90 \times w \times 40 \]
First, calculate \(90 \times 40\):
\[ 90 \times 40 = 3600 \]
Now we can rewrite the equation as:
\[ 162,000 = 3600 \times w \]
Next, solve for \(w\):
\[ w = \frac{162,000}{3600} \]
Calculating the division:
\[ w = 45 \]
Thus, the width of the box is 45 cm.