Does eating vegetables instead of delicious foods affect how long you live? Given a population life expectancy?

Does eating vegetables instead of delicious foods affect how long you live? Given a population life expectancy of 75 years with population standard deviation 5 years, What is the z-value for a random sample of 25 vegans who live to an average age of 73? Does this alter life expectancy at a .05 level of significance? Type the z-value in box 1 to two decimal places (e.g. 3.45), and in box 2 type either yes or no (yes if this is statistically significant and you reject the null, no if it is not significant and you fail to reject the null).