sky high
Circumference (around).
As long as it has the round enclosure, it is safe.
Jumpsport.com sells enclosures that work for 15-16' trampolines. Look at the model 480XT.
I've read $12 to $15 per square foot
Yes, Walmart does carry trampolines in their Supercenters. A 12' trampoline with enclosure is $235. A 15' trampoline with enclosure is $298.
Fifty
15 foot by 15 foot is an area of 225 square feet.
An air quality index of 0-15 is considered good, with little to no risk to health. This level indicates that the air quality is clean and poses minimal health concerns for the general population.
I would guess about 3-4 kids but I have been on a 15 ft trampoline with 6 kids for 2 weeks strait and no one got hurt so it is really up to the supervisor.
15 centimeters is 1/2 foot.
10-15 knots in a good gust of wind
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