Local government is worried that runoff from a corporate farm has caused water in a nearby stream to become acidic. The pH is used to measure the acidity/alkalinity of a substance. Pure water, for instance, has a pH of 7, and smaller pH values indicate acidity, while larger values indicate alkalinity. A contractor is hired to test the hypothesis that the water is significantly acidic.

H0: μ = 7

HA: μ < 7

The contractor took 27 water samples and found an average pH of 6.3 with a sample standard deviation of 1.86. What is the test statistic for this sample?

Give your answer to 2 decimal places. For help on how to input a numeric answer, please see "Instructions for inputting a numeric response."