To determine the corresponding measure in a similar figure that is 3 times as big, we first need to figure out what the missing dimension of the original figure is.
We know that for a shape that has an area of 20 square inches and one dimension of 4 inches, we can find the other dimension by using the formula for the area of a rectangle (if we assume that the figure is rectangular, as it is a common interpretation):
\[ \text{Area} = \text{length} \times \text{width} \]
Let \(w\) be the unknown dimension. We have:
\[ 20 = 4 \times w \]
To solve for \(w\):
\[ w = \frac{20}{4} = 5 \text{ inches} \]
Now we know the dimensions of the original figure are 4 inches and 5 inches.
Since the similar figure is 3 times as big, we multiply each dimension by 3:
The dimensions of the larger figure will be:
\[ 4 \text{ inches} \times 3 = 12 \text{ inches} \]
\[ 5 \text{ inches} \times 3 = 15 \text{ inches} \]
Therefore, the corresponding part in the similar figure that is 3 times as big is:
12 inches for the dimension initially measuring 4 inches, and 15 inches for the dimension initially measuring 5 inches.