A part is sold 6 for $7.50 or 10 for $12.00. How much less does each part cost in the larger pack?

Correct answer to question 78 (Arithmetic Reasoning): 5 cents

Method

Reduce both to a price per part before comparing: 7.50 / 6 = $1.25 and 12.00 / 10 = $1.20. The difference is 5 cents each. Comparing the pack prices directly tells you nothing useful.