Could I get any marks for this question?

Edexcel GCSE mark schemes say that if the correct answer is obtained from the incorrect method then 0 marks should be awarded. The image I have attached is for a mark scheme of a question on histograms. I put an answer of 19 for 15b) which is right. However, this was a complete guess! I put some random working to make it seem as if I could work it out, but the Edexcel mark schemes say that 0 marks should be awarded in this instance. Is this definitely the case or is there a chance I can get a mark?