For slow start :
1st RTT Send 1 mss
2nd RTT Send 2 mss
3rd RTT Send 4 mss
4th RTT Send 8 mss
so total 4 RTT Required..
a. So total time take = 4*RTT = 4*10 = 40 usec.
b. Throughput for 1st rtt= 100/(10*10^6) = 10MBPS
c. Total Throughput = (Throughput for 1st rtt+Throughput for 2nd rtt + Throughput for 3rd rtt + Throughput for 4th rtt)
= [100/(10*10^6) + 2*100/(10*10^6) + 4*100/(10*10^6) + 8*100/(10*10^6)]
= [10 +20+40+80] MBPS = 150 MBPS
d. Average Throughput = (Throughput for 1st rtt+Throughput for 2nd rtt + Throughput for 3rd rtt + Throughput for 4th rtt)/4
= [100/(10*10^6) + 2*100/(10*10^6) + 4*100/(10*10^6) + 8*100/(10*10^6)]/4
= [10 +20+40+80]/4 MBPS = 150/4 = 37.5 MBPS