# Model why async helps I/O-bound work

Canonical URL: <https://datadriven.io/problems/model-why-async-helps-io-bound-work-three-api-calls-take-0-78bc85d4>

Domain: Python · Difficulty: medium

## Problem

Model why async helps I/O-bound work. Three API calls take 0.3, 0.5, 0.2 seconds of WAITING. Run sequentially the total time is the sum; run concurrently (overlapping the waits) the total time is the longest single wait. Print the sequential total then the concurrent total, each rounded to 1 decimal, one per line. (Model it with plain arithmetic, no asyncio.)

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