Since $81=9^2$ and $100=10^2$, $98$ is between them, so $\sqrt{98}$ is between $9$ and $10$. A quick check: $9.9^2=98.01$, so $\sqrt{98}\approx9.90$ to the nearest hundredth.

Since $14^2=196$ and $15^2=225$, $221$ is between them and closer to $225$, so $\sqrt{221}$ is a little less than $15$. Calculator: $\sqrt{221}\approx14.866\dots$, which rounds to $14.9$ to the nearest tenth.

Since $\sqrt{49}=7$ and $\sqrt{64}=8$, $\sqrt{50}$ is just over $7$. Calculator: $\sqrt{50}\approx7.071\dots$, which rounds to $7.07$ to the nearest hundredth.