To convert the dimensions of the grid drawing from a scale factor of 1 box = 6 inches to a scale factor of 1 box = 12 inches, we first need to determine the length in inches of the original drawing.
In the original drawing, with a scale of 1 box = 6 inches, the length is: \[ 10 \text{ boxes} \times 6 \text{ inches per box} = 60 \text{ inches} \]
Now, if we want to represent the same actual length of 60 inches with a new scale factor of 1 box = 12 inches, we can find the number of boxes needed to represent that length.
To find the number of boxes at the new scale, we divide the total length in inches by the new scale factor: \[ \text{Number of boxes} = \frac{60 \text{ inches}}{12 \text{ inches per box}} = 5 \text{ boxes} \]
Therefore, the length of the boxes in the new drawing, under the scale factor of 1 box = 12 inches, will be:
C. 5