Mensuration Practice Test 8

Obviously,
$\frac{\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{bigger}\mathrm{cube}}{\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{cmaller}\mathrm{cube}}$ = $\frac{3\times 3\times 3}{1\times 1\times 1}$ = $\frac{27}{1}$
= 27 cubes

Number of cubes which are not painted
Face (A + B) + (c + d) + (e + f )
(9 + 9) + (3 + 3) + (1 + 1)
18 + 6 + 2 = 26
27 − 26 = 1 cube is unpainted.