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Let $a$ represent the amount of tests taken previously and $x$ the mean of the scores taken previously. We can write the following equations: $$\frac{ax+11}{a+1}=x+1(1)$$ $$\frac{ax+33}{a+3}=x+2(2)$$ Multiplying equation $(1)$ by $(a+1)$ and solving, we get: $$ax+11=ax+a+x+1$$ $$11=a+x+1$$ $$a+x=10(3)$$ Multiplying equation $(2)$ by $(a+3)$ and solving, we get: $$ax+33=ax+2a+3x+6$$ $$33=2a+3x+6$$ $$2a+3x=27(4)$$ Solving the system of equations for $(3)$ and $(4)$, we find that $a=3$ and $x=\boxed{7}$.