In a paged memory, the page hit ratio is 0.40. The time required to access a…
2018
In a paged memory, the page hit ratio is 0.40. The time required to access a page in secondary memory is equal to 120 ns. The time required to access a page in primary memory is 15 ns. The average time required to access a page is ________.
- A.
105
- B.
68
- C.
75
- D.
78
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Correct answer: D
Solution:
Identify probabilities:
Page hit ratio = 0.40
Page miss ratio = 1 − 0.40 = 0.60
Use the average access time formula:
Average time = (hit ratio × primary access time) + (miss ratio × secondary access time)
Substitute the given values:
Average time = 0.40 × 15 ns + 0.60 × 120 ns
Average time = 6 ns + 72 ns = 78 ns
Answer: 78 ns
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