This question is for Air conditioning principles and systems

This question is for Air conditioning principles and systems course ( Fourth edition )

You are designing .a duct system using galvanized steel round duct and looking at the flow characteristics you want to keep the friction loss at 08 in w per 100 feet or less at a velocity of 600 feet per minute. What is the CFM you can achieve and the size of the duct? ___ CFM ___inches

Using the standard formulas of HVAC we can get,