Answer: c. 12.5%
Explanation:
To find the percent increase in the student's wage, we need to calculate the difference between his old wage of $12 per hour and his new wage of $13.50 per hour, and then divide that difference by his old wage and multiply by 100%. This gives us the following calculation:
(13.50 - 12) / 12 * 100% = 1.50 / 12 * 100% = 0.125 * 100% = 12.5%
Therefore, the student's wage increased by 12.5%, which is the same as saying it increased by 0.125 or 1.25/10. This corresponds to answer choice c.