I'm trying not to pick on Kevin Gao of Management Consulted. He was just an analyst, and seems like a well-meaning kid. He's trying to help people break into management consulting, even though it's the worst time in the last 20 years to try and get into consulting. So I applaud him for his entrepreneurism and his teaching attitude.
Never trust an analyst's analysis.
If the question is “How many baseballs would fit into a Boeing 747?”, don’t say “I’d estimate the cubic volume of a 747 to be between 10,000 and 20,000 square feet”. Stick with one number. Ranges provide unnecessary complication and will double the number of calculations.
"Well, I want to estimate the 747's interior volume by approximating it as a cylinder. I know that the formula for a cylinder's volume is Volume = Pi * radius^2 * length.
I'm going to assume that the length of a 747 cabin is 300 feet, since I've been in one and it seemed like the length of a football field. Then, I want to think about the radius. I remember the seating configuration in coach as 3 seats, 5 seats, and 3 seats, plus 2 aisles. If I assume that each seat is 2' in width, and the aisles are 2' as well, that gives me 26 feet in diameter, so I'm assuming the radius is 13 feet.
Now, I have Volume = Pi * 13^2 * 300. To make the math simpler, I'm going to round pi to 3. Running the numbers... I get 152,000 cubic feet. I want to round this up a little bit since I rounded pi down, so I'm going to estimate 160,000 cubic feet as the interior volume of a 747."
It's better to be right than to be fast.