Hypothesis testing — practice question

Anton thinks that $10\%$ of students at his college are left-handed. Aliya thinks this is an underestimate. She intends to carry out a hypothesis test of the null hypothesis $p = 0.1$ against the alternative hypothesis $p > 0.1$, where $p$ is the true proportion of students at the college who are left-handed. She takes a random sample of $20$ students from the college. She will reject the null hypothesis if at least $5$ of these students are left-handed.