The level of various substances in the blood of kidney dialysis

The level of various substances in the blood of kidney dialysis patients is of concern because kidney failure and dialysis can lead to nutritional problems. A researcher performed blood tests on several dialysis patients on 6 consecutive clinic visits. One variable measured was the level of phosphate in the blood. Phosphate levels for an individual tend to vary normally over time. The data on one patient, in milligrams of phosphate per deciliter (mg/dl) of blood, are given below.
5.7 4.9 5.6 5.0 7.0 4.3

(b) Use the t procedures to find the margin of error for a 90% confidence interval for this patient’s mean phosphate level.

(c) Use the t procedures to give a 90% confidence interval for this patient’s mean phosphate level.