<PRE><B>Question 552709</B>
The suface area (SA) of a rectangular prism of length (L), width (W) and height (h) can be expressed by:
SA = 2(L*W)+2(L*h)+2(W*h) This is just adding the areas of the 3 identical pairs of the six faces of the prism. 
SA is given as 242.2 sq.in.
Substitute the given values: SA = 242.2, L = 4.7, and W = 6.4
242.2 = 2(4.7*6.4)+2(4.7h)+2(6.4h) Divide by 2 to simplify a bit.
121.1 = (4.7*6.4)+4.7h+6.4h
121.1 = 30.8+11.1h Subtract 30.8 from both sides.
90.3 = 11.1h Divide both sides by 11.1
h = 8.13515 inches.
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