Chlorine concentration in a municipal water supply is a uniformly distributed random variable that ranges between 0.76 ppm and 0.99 ppm.

With that information you can calculate the mean or average.

Given that it is uniformly distributed in that range, it means that the function is symmetrical around the mean, i. e. the mean is at the center of the distribution = > mean = (0.99 + 0.76) / 2 = 0.875