If you own the bike, you can use the bathroom scale. If you go the shop, they can measure it on their scale (if they don't want to do it, they are not serious shop).
For that type of bike (price, frame), it is hard to expect to be less than 30 lbs.
If you are concerned with the weight, you should check Rockhopper. Also, disc brakes bring 1 or more pounds, comparing to V brakes.
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!