Jamie buys 4 put option contracts.
Each contract covers 1,000 shares, so:
4 × 1,000 = 4,000 shares
The strike price is $40 and Apple falls to $30, so the put option is worth:
$40 - $30 = $10 per share
However, Jamie paid a premium of $3 per share, so his net profit is:
$10 - $3 = $7 per share
Total profit:
$7 × 4,000 = $28,000
Another way to show it:
Gross payoff = ($40 - $30)(4,000) = $40,000
Cost of options = $3(4,000) = $12,000
Profit = $40,000 - $12,000
= $28,000
Therefore, Jamie earns a $28,000 profit over the 3-month period.