Industrial pollution often makes water supplies either acidic (pH < 7.0) or basic (pH >7.0). An industrial company that dumps waste water into a nearby river claims that the mean pH level of the water in the river near the site of the company's discharge is 7.0, so it is neutral. You, as an environmentalist, randomly select 19 water samples and measure the pH of each. The sample mean and standard deviation are 6.9 and 0.24, respectively. Assume the population of pH levels in all possible water samples is normally distributed. a. Is there enough evidence to reject the company's claim at the 5% significance level? How about at the 10% level? b. Compute 90% and 95% confidence intervals for the mean pH level. Are the results consistent with what you found in part (a)