The viscosity of a liquid is checked every half-hour during one 3-shift day. Prepare a run chart ...

The viscosity of a liquid is checked every half-hour during one 3-shift day. Prepare a run chart. What does the run chart indicate? Data are 39, 42, 38, 37, 41, 40, 38, 36, 40, 36, 35, 38, 34, 35, 37, 36, 39, 34, 38, 36, 32, 37, 35, 34, 33, 35, 32, 32, 38, 34, 37, 35, 35, 34, 31, 33, 35, 32, 36, 31, 29, 33, 32, 31, 30, 32, 32, and 29