What is the statistic value that is used to indicate normal or abnormal behavior?

Steps to Solve

1. Calculate Total Accesses

First, we need to find the total number of accesses by summing up the number of accesses for each file.

[ \text{Total accesses} = N_0 + N_1 + N_2 + N_3 = 10 + 28 + 34 + 56 ]

2. Compute Total Accesses

Calculating the total:

[ \text{Total accesses} = 10 + 28 + 34 + 56 = 128 ]

3. Calculate Access Rates

Next, we will calculate the access rate for each file using the formula ( H_i = \frac{N_i}{\text{Total accesses}} ).

• For ( F_0 ): [ H_0 = \frac{N_0}{\text{Total accesses}} = \frac{10}{128} ]

• For ( F_1 ): [ H_1 = \frac{N_1}{\text{Total accesses}} = \frac{28}{128} ]

• For ( F_2 ): [ H_2 = \frac{N_2}{\text{Total accesses}} = \frac{34}{128} ]

• For ( F_3 ): [ H_3 = \frac{N_3}{\text{Total accesses}} = \frac{56}{128} ]

4. Calculate Values

Now, compute the values for each access rate:

[ H_0 = \frac{10}{128} = 0.078125 \approx 0.078 ]

[ H_1 = \frac{28}{128} = 0.21875 \approx 0.219 ]

[ H_2 = \frac{34}{128} = 0.265625 \approx 0.266 ]

[ H_3 = \frac{56}{128} = 0.4375 \approx 0.438 ]

5. Calculate Mean Access Rate

Finally, find the mean of the access rates:

[ \text{Mean} = \frac{H_0 + H_1 + H_2 + H_3}{4} = \frac{0.078 + 0.219 + 0.266 + 0.438}{4} ]

Calculating the mean:

[ \text{Mean} = \frac{1.001}{4} = 0.25025 \approx 0.250 ]