Chapter 11, Problem 5E

Explanation of Solution

Performance that is improved after adding new software:

• The information about the fault rate of the cache that is produced in the system is given.
• When the fault rate is increased the performance gets decreased.
• After installation of new product the fault rate is considered to be reduced
• Reading of the old system and the new system are provided at the different times.
• Calculating harmonic mean for comparing the performance of each.

Consider there are n reading which are expressed are in the form rate it required to calculate harmonic mean.

Calculating the harmonic mean is made by taking the sum of the reciprocals by dividing the number n by the sum obtained.

Consider the following table:

Serial no	Fault rate that occurred before	Fault rate that occurred after
1	35%	45%
2	42%	38%
3	12%	10%
4	20%	22%

Calculating the harmonic mean:

System Before:

$\begin{array}{l}=\frac{4}{(\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$0$}\right.}\end{array}$