At a time of 6 pm and 9 pm, the inflow rates into a river are 25 m3/s and 36 m3/s respectively. The outflow at the downstream section at 6 pm is observed to be 20 m3/s. The Muskingum coefficient C0 and C1 are known to be 0.05 and 0.60 respectively. The outflow at the downstream section at 9 pm is ______
1
23.8 m3/s
2
27.0 m3/s
3
30.5 m3/s
4
31.0 m3/s