4. The tobacco manufacturer "Karólína Tóbak" advertised that their best-selling cigarettes contained a maximum of 40mg of nicotine. A consumer spokesperson tested 20 cigarettes randomly selected from...

Extracted text: 4. The tobacco manufacturer "Karólína Tóbak" advertised that their best-selling cigarettes contained a maximum of 40mg of nicotine. A consumer spokesperson tested 20 cigarettes randomly selected from different packs and found that the average nicotine content in the twenty cigarettes was 42mg and the standard deviation was 4mg. The nicotine content can be expected to follow a normal distribution. Perform an appropriate hypothesis test to see if the average nicotine content differs from 40mg. Show all six steps. Use a = 0.05.