Question

The cost of a square slab is proportional to its thickness and also proportional to the square of its length. What is the cost of a square slab that is 3 meters long and 0.1 meter thick? gmat

Answer 1

$cost \: \: \alpha \: \: t( {l}^{2} ) \\ cost = kt {l}^{2}$

since nothing is said about k... hence let k =1

$cost = t {l}^{2} \\ cost = 0.1 \times {3}^{2} = 0.9 \:$