ITPEC FE Morning October 2021 Question 12
ITPEC FE Morning October 2021 — Question 12 of 80
Cache Hit Ratio Calculation — find hit ratio from effective access time.
Given: cache = 100 ns, main memory = 900 ns, effective = 250 ns.
Formula:effective = h × cache_time + (1 − h) × main_time
Solution:
- 250 = h × 100 + (1 − h) × 900
- 250 = 100h + 900 − 900h
- 250 = 900 − 800h
- 800h = 650
- h = 650 / 800 = 0.8125 ≈ 0.81
Why not others:
- (a) 0.25 — gives effective = 700 ns
- (b) 0.35 — gives effective = 620 ns
- (c) 0.73 — gives effective = 316 ns
Key rule: Rearrange effective = h × cache + (1 − h) × main to solve for h.
AI-generated — may contain errors
The original exam layout is preserved in the image so diagrams, formulas, tables, and code remain accurate.
This question comes from an official ITPEC past paper. ITPEC Practice is an independent study tool and is not affiliated with ITPEC. See the official FE past-paper collection or Report an issue.