A worker was exposed over his work shift to various levels of n-pentane as shown in the tabulated exposure history that follows. The TLV-TWA for n-pentane is 600 ppm. 2.0 hours 3.0 hours 1.5 hours 1.5 hours 475 ppm 725 ppm 600 ppm 475 ppm a. What was this worker 8-hour TWA exposure to n-pentane? (10 pts.) b. Was this exposure a violation of the 8-hour TLV-TWA? (5 pts.)