A worker uses Chemical X all day to perform Tasks A, B and C. An industrial hygienist performs personal sampling for each task during one 8-hour work...

A worker uses Chemical X all day to perform Tasks A, B and C. An industrial hygienist performs personal sampling for each task during one 8-hour work shift and obtains the following data:

Task A took 3 hrs and had a concentration of 40 mg/m3

Task B took 4 hrs and had a concentration of 25 mg/m3

Task C took 1 hr and had a concentration of 70 mg/m3

What was this worker's 8-hour time weighted average exposure to chemical X? Please show work

 _____ mg/m3