Biologist researching the effects of adding limestone sand as buffer acid rain effects in streams, monitored the pH levels of 2 streams each month for 36 months. the first stream had a mean pH level of 6.8 with a standard deviation of 2.3 the control stream had a mean pH level of 9.2 with a SD of 1.5. Assume a .05 significance level for testing the claim that the mean pH of the first stream was less (more acid) than the mean pH of the control stream. Also assume the 2 samples are independent simple random samples selected from normally distributed populations, but do not assume the population standard deviation are equal.

find the t test statistic. Give answer with two decimals, e.g., 9.87