From generation to generation, the mean age when smokers first start to smoke varies. however, the standard deviation of that age remains constant at around 2.1 years. a survey of 44 smokers of this generation was done to see if the mean starting age is at least 19. the sample mean was 18.1 with a sample standard deviation of 1.3. do the data support the claim at the 5% level? note: if you are using a student's t-distribution for the problem, you may assume that the underlying population is normally distributed. (in general, you must first prove that assumption, though.)