An old medical textbook states that the mean sodium level for healthy adilts is 139meq per liter of blood

An old medical textbook states that the mean sodium level for healthy adilts is 139meq per liter of blood. a medical researcher believes that, because of modern dietary habits the mean sodium level for healthy adults u now differs from that given in the textbook. a random sample of 35 healthy adults is evaluated. The mean sodium level for the sample is 135meq per liter of blood. Its is known that the population standard deviation of adult sodium levels is 10meq. Assume that the population is normally distributed. can we conclude at the 0.05 level of significance that the population mean adult sodium level differs from that given in the textbook