How would one change (below) this from a 2 sample T test to a one sample t test?

I have chosen to make my one sample t test on high school students. A national college rating group has determined that high school students who attend an early college high school are more likely to excel in their graduate school programs.

A t test is used to determine the standard deviation for a population when the sample mean is known and the population mean is unknown (Steinberg, 2011, p. 194). Since the sample must be between 25 and 30, I chose 25 early college high school students for my study.

My independent variable is the completion of early college high school and my dependent variable is acceptance into graduate programs at prestigious universities.

The null hypothesis for my study would suggest that there is no significant difference in the dependent variable expectation completion of early college high school and acceptance into graduate programs at prestigious universities.

The alternative hypothesis would state that the likelihood that an early college high school student will be accepted into a graduate program is below the expected outcome of acceptance.

I would expect the null hypothesis to be rejected in this study, as I would expect that the likely result to be that early college high school students will more so be accepted in a graduate program.

A confidence interval is an interval estimate having a specified probability of including the population usually 95% or 99% (Steinberg, 2011, p. 218). A 95 percent confidence interval of the mean for this study would say that there is a strong possibility that the results of the research study would reveal the expected hypothesis that the researcher is seeking. The 99% confidence interval reveals that the hypothesis being sought is most accurate.