Answer 1: minimum required flow rate of fresh air is 0.57 m^3/ses
Explanation: since the minimum requirement per person is 30 L/sec
Converting to m^3 it becomes
30/1000 = 0.03 m^3/sec
For 19 heavy smoker we will require
19 * 0.03 = 0.57m^3/sec
Answer 2: diameter of the duct will be 0.3m
Explanation: since flow rate is
Q =0.57m^3/sec
Also
Q = AV (continuity equation)
Where A is the duct area and V is the velocity of air flow in m/sec
0.57m^3/sec = A * 8m/sec
A = 0.57/8 = 0.071m^2
Area of the duct is that of a circle
A = 3.142 *(d^2 ÷4)
d^2 = (0.017 * 4)/3.142 = 0.09
d is square root of 0.09
d = 0.3m
