A company that manufactures radios has determined that retailers are likely to purchase \( x \) radios at a price of 

\( ( x ) = 10 - \frac { x } { 1000 } ,\) 

rand per unit. If the company's fixed costs are \( R 5 \) \( 000 \) and their variable cost is \( R 2 \) per unit, determine the company's profit function. 

1. \( \pi ( x ) = 10 - \frac { x } { 1000 } \) 

2. \( \pi ( x ) = 10 - \frac { x } { 1000 } - 5000 + 2 x \) 

3. \( \pi ( x ) = - \frac { x ^ { 2 } } { 1000 } + 8 x - 5000 \) 

4. \( \pi ( x ) = 10000 - x\)