- Marginal Revenue Function: \( R'(x) = 250 - 0.02x \)
- \( R(72) - R(71) \approx 248.57 \)
- \( R'(72) \approx 248.56 \)
- Profit Function: \( P(x) = -0.01x^2 + 50x - 10000 \)
- Marginal Profit Function: \( P'(x) = 50 - 0.02x \)
\[
\boxed{R'(x) = 250 - 0.02x, \quad R(72) - R(71) \approx 248.57, \quad R'(72) \approx 248.56}
\]