statstics

1)  Review the paired samples t test equation below and answer the questions:1a. What is d with the bar over it called and how do you find it?1b. What is the S (with subnotation of d) called?1c. What is n?2)   What is the estimated standard error for a paired sample t test using the following data:  Standard deviation of the difference score = 5 and n=100?3)  In a paired samples t test, explain the logic of difference scores (why do you need to find them to make conclusions about your research) and why do you compare it to a population mean often designated as zero (µ = 0)?