Before a three-for-one stock split, the shares outstanding were 5,000 shares at $12 par.

After the three is to one split, for every one old share, there will be three new shares.

So number of new shares = 5000*3 = 15,000 shares

Since the number of shares increased three fold, the price per share will decrease by three fold.

So the price per share after split = 12/3 = $4

So, after the split, there will be 15,000 shares at $4 per share