The math seems to be off in a few places:
1. When solving for the arrival rate λ, it should be λ=ρ/S instead of λ=S/ρ.
2. Calculating the arrival rate λ with the correct formula results in 9 requests/second instead of 10 request/second.
3. Calculating the new utilization ρ should be 0.05x9 instead of 0.05x10.
The result of the calculated utilization ρ is correct (0.45), so is the calculated new latency.
edit: new lines
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