An algorithm takes 20 seconds to execute on a single 2.4G processor. 40% of the algorithm is sequential.Assuming zero latency and perfect parallelism in the remaining code

1. Approximately how long should the algorithm take on a parallel machine made of 8 2.4Gprocessors? the asnwer is 9.5

2. Suppose that we can add (with perfect scalability) any number of 2.4 G processors to the system.What is the fastest time that can be achieved? the asnwer is 8

I do understand how we got 9.5 for the first question, but I am not sure how we got 8 for the second one. what i now is perfect scalability is 1/f so that is 1/.4=2.5 times faster. can you please help me. Thank you