What is the error rate for random guessing?
Random guessing of value of whcih column? For example random guessing the gender of each row is: probability of it is male but guess female + vice versa which is $\frac{7}{10}\times\frac{1}{2} + \frac{3}{10}\times \frac{1}{2} = \frac{1}{2}$ and it means the error of random guessing the value of Gender is $50\%$.
Also you can compute for the others by the possible value for each column. For example for the Hair Length the error would be $\frac{2}{3}$ or $66.66\%$.