After reading a sample IELTS Writing Task 1 answer on http://www.ielts-exam.net/academic_writing_samples_task_1/874/
I have some questions regarding comparisons given in the answer.

1. 'Girls achieved by far their best results in Computer Science, with a pass rate of 56.3%, which was considerably/much/around 14% higher than the boys.'
I think this sentence contains an illogical comparison. I would say: 14% higher than the boys' or 14% higher than those of the boys.

2. 'The (only/one/single) subject where boys’ results were better than girls was Geography ...'
Again, I think it is an illogical comparison. I would say: were better than girls' or were better than those of the girls.

Thank you in advance.