Use the following data to construct a 99% confidence interval to estimate the difference D. Assume the differences are normally distributed in the population. What is the lowervalue of the interval?

(Round your answers to 2 decimal places, e.g. 1.75.)

Respondent	Before	After
1	47	63
2	33	35
3	38	36
4	50	56
5	39	44
6	27	29
7	35	32
8	46	54
9	41	47