Concept:
Power is defined as the work done per unit time. When a man climbs a height, he does work against gravity for both his own mass and the load mass. \( P = \frac{(M_{man} + M_{load})gh}{t} \).
Step 1: Set up the power equation.
Given \( P = 1323 \text{ W} \), \( M_{load} = 60 \text{ kg} \), \( h = 30 \text{ m} \), \( t = 20 \text{ s} \), and assuming \( g = 9.81 \text{ ms}^{-2} \):
$$ 1323 = \frac{(M_{man} + 60) \times 9.81 \times 30}{20} $$
Step 2: Simplify the equation.
$$ 1323 = (M_{man} + 60) \times 9.81 \times 1.5 $$
$$ 1323 = (M_{man} + 60) \times 14.715 $$
$$ M_{man} + 60 = \frac{1323}{14.715} \approx 90 $$
Step 3: Solve for \( M_{man} \).
$$ M_{man} = 90 - 60 = 30 \text{ kg} $$
$$\boxed{30 \text{ kg}}$$