1. An industrial company claims that the mean pH level of the water in a nearby river is 6.8. You randomly select 19 water samples and measure the pH of each. The sample mean and standard deviation...

1. An industrial company claims that the mean pH level of  the water in a nearby river is 6.8. You randomly select 19 water samples and measure the pH of each. The sample mean and standard deviation are 6.7 and 0.24,respectively.  Is there enough evidence to reject the company’s claim at α = 0.05?  Assume the population is normally distributed .