Mineral flotation in water study. Refer to the Minerals Engineering (Vol. 46–47, 201...

Mineral flotation in water study. Refer to the Minerals Engineering (Vol. 46–47, 2013) study of the impact of calcium and gypsum on the flotation properties of silica in water, Exercise 2.48 (p. 53). Recall that 50 solutions of deionized water were prepared both with and without calcium/gypsum, and the level of flotation of silica in the solution was measured using a variable called zeta potential (measured in millivolts, mV). The data (simulated, based on information provided in the journal article) are reproduced in the tables at the bottom of the page. Which of the two zeta potential distributions, without calcium/gypsum or with calcium/gypsum, can be approximated by a normal distribution?

Reference: Exercise 2.48