$[15/10]<1\mathrm{.}9>$ Assume that we make an enhancement to a computer that improves some mode of execution by a factor of $10.$ Enhanced mode is used $50\%$ of the time, measured as a percentage of the execution time when the enhanced mode is in use. Recall that Amdahl$$s Law depends on the fraction of the original, unenhanced exe$-$ cution time that could make use of enhanced mode. Thus we cannot directly use this $50\%$ measurement to compute speedup with Amdahl$$s Law.

a$.[15]<1\mathrm{.}9>$ What is the speedup we have obtained from fast mode?

b$.[10]<1\mathrm{.}9>$ What percentage of the original execution time has been converted

to fast mode?