Many of studies on height versus age have been conducted and various graphs plotted. This question calls for use of such graphs to establish height at a certain age. A graph that can be used in this case is attached.
At age of 2 years, the height is 2'8" = (2*12)+8 = 32"
From the graph, this lies between 5% and 25% percentiles. Assuming that one reaches adult at 18 years old, the height can be read from the graph to be approximately 62".
Height at 18 years = 62" = 62/12' = 5'2" = 5 feet and 2 inches.