acc to me ans should be like this..
for register: (0.10*1)=0.10 cycles
for immediate= it should be zero
for direct = 0.30*2 =0.60 cycles (becz 1 mem ref and for 1 mem ref 2 cycles are required)
mem indirect= 0.20*4=0.80cycles
index = 0.20*6=1.2cycles
now 0.10+0.60+0.80+1.2 =2.7 cycles
1cycle required 1ns time
so Tavg =2.7 ns
1 instruction time =2.7 ns
so in 1 sec=1/2.7 ns
that is 370.37 million