A 24 foot tall tree casts a shadow that is 18 foot long. At the same time, Nathan casts a 4-foot shadow. How tall is Nathan?

Using similar triangles, we can set up the proportion:

(Height of tree)/(Length of tree's shadow) = (Height of Nathan)/(Length of Nathan's shadow)

Plugging in the given values:

(24 ft)/(18 ft) = (Height of Nathan)/(4 ft)

Cross multiplying:

(24 ft)*(4 ft) = (18 ft)*(Height of Nathan)

96 ft = 18 ft * (Height of Nathan)

Dividing both sides by 18 ft:

(96 ft)/(18 ft) = Height of Nathan

Simplifying:

5.33 ft = Height of Nathan

Therefore, Nathan is approximately 5.33 feet tall.