The price of a European call on a stock with a strike price of $10 is $7. The price of a European call on the same stock with a strike price 15 is $3. The maturities of these two options are the same. An investor creates a bull spread using these two options. If the underlying stock price at the maturity is $11. What is the profit earned by this investor? Please provide your answer in dollars without the dollar sign (rounded to the nearest cent).