A student asked me about the 'yes, no, not given' question below.
Thirty per cent of deaths in the United States are caused by smoking-related diseases.
Relevant part of the passage:
Smoking, it is believed, is responsible for 30 per cent of all deaths from cancer and clearly represents the most important preventable cause of cancer in countries like the United States today.
(Click here to see the full passage and exercise)
The official correct answer to this question is 'no'. However, the student who asked me about this question believes that we should answer 'not given'. His reason for this is that we have no information about deaths that aren't caused by cancer. Maybe smoking does cause 30% of all deaths.
What do you think? Is this student 'overthinking'? How can we explain why 'no' is the correct answer?