Final answer:
To find the market price of the stock per share, multiply the P/E ratio (12) by the earnings per share ($2.50), which results in a market price of $30.00 per share.
Step-by-step explanation:
If the P/E ratio (Price-to-Earnings ratio) of a company's common stock is 12 and its earnings were $2.50 per common share, you can calculate the market price of the stock per share by multiplying the P/E ratio by the earnings per share (EPS). The formula to calculate the stock price is:
P/E ratio x EPS = Market Price per Share
Therefore, 12 (P/E ratio) x $2.50 (EPS) gives us $30.00 as the market price per share.
Thus, the answer to the student's question is: 3) $30.00.