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(13-43) A 15-cm-radius air duct is used to replenish the air of a room 8.2 m X 5.0 m X 3.5 m every 1
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(13-43) A 15-cm-radius air duct is used to replenish the air of a room 8.2 m X 5.0 m X 3.5 m every 12 min. How fast does the air flow in the duct?