Nerve impulses have been found to travel as fast as 100 m/s. what could account for the difference between your answer to question 5 and this value obtained by researchers?

There are many factors that can alter the nerve traveling speed. It can be the calculation error from estimating the nerve fiber because you are not measuring the actual nerve length. Electrolyte level is also has a big impact on the membrane potential. Another drug that influences neurotransmitter that the subject take also might alter the speed.