A block of wood has dimensions 10cm x 10cm x 80cm. The block is painted red and then cut evenly at the 40 cm mark, parallel to the sides, to form two rectangular solids of equal volume. What percentage of the surface area of each of the new solids is not painted red? Choose the correct choice
A) 5.6 %
B) 8.4 %
C) 11.2 %
D) 14.8 %
E) 17.5 %

Rationale: the area of each half is 100 + 4 ( 400 ) + 100 = 1800 the area that is not painted is 100 . the fraction that is not painted is 100 / 1800 = 1 / 18 = 5.6 % the answer is a .
Answer: A