I would bet good money that you wouldn't see much improvement with the new domain. The video that saibose posted says it all - Google is putting much less emphasis on keyword rich domains these days.
Think of some really successful websites that you know...a good number of them don't have a keyword in their domain:
-Facebook
-Google
-Twitter
Adding a keyword to your domain may add some minor boost, but it's not going to take you up too high.
Do you have good quality links to your site? If so, then if you change your name you'll lose some of the power of those links. (If you redirect your old domain to your new one you'll retain some link juice though). If you haven't got good links to your site then this is your answer. Get people linking to you and you will rise up to the top.
Is your site really rocketproblems.com? I couldn't find it or rocketmathproblems.com online.