Correct Answer - Option 3 : 835 Sabin-m
2
\(R{T_{60}} = \frac{{0.167V}}{{Sa}}\)
Where RT60 is the reverberation time (to drop 60 dB), V is the volume of the room (m3), S is the total surface area of the room (m2), a is the average absorption coefficient of room surface (Sabine/m2) and Sa is the total absorption in sabines.
\(T = \frac{{0.167V}}{{Sa}}\)
T = 1.5 seconds
V = 7500 m3
Sa = 835 Sabin-m2