A sample of 27 paired observations generates the following data: dd = 1.8 and s2DsD2 = 3.6. Assume a normal distribution. (You may find it useful to reference the appropriate table: z table or t table)

a. Construct the 90% confidence interval for the mean difference _D. (Round final answer to 2 decimal places.)

Confidence interval is 0.62 to 2.98 - this is not the answer. Can someone please explain this to me?