For the final project of an analytical chemistry laboratory course, the students were asked to quantify the lead (Pb2+Pb2+) content in a drinking water sample. To receive a passing grade for the project, the students must produce a result (Pb2+Pb2+ concentration) that agrees with the result obtained by the course professor, who was using the same method, at the 95% confidence level. The mean (x), standard deviation (sx) and number of replicate measurements (n) are shown for the data obtained by the professor (p) and one student (s) chosen atrandom.

Student:s=4.070ppb s=0.259ppbs=6

Professor:p=4.720ppb p=0.170ppbp=6

Calculate the tvalue.