Jenna wants to make a park bench as part of her family's miniature railroad train display. If the display is built to scale where 3 cm = 1 ft, and Jenna is modeling her bench after a bench with a length of 5 ft, what will the length of Jenna's model be?

First, we need to convert the length of the full-size bench from feet to centimeters.

5 ft * 12 inches/ft * 2.54 cm/inch = 152.4 cm

Now, we need to apply the scale factor of 3 cm = 1 ft to find the length of Jenna's model bench.

152.4 cm / 3 = 50.8 cm

Therefore, the length of Jenna's model bench will be approximately 50.8 cm.