Answer to Question 1
ANS: B
Because 1 SD is 0.1 g/dL, 2 SD = 0.2 g/dL. Thus 95.5 of the results lie between 13.6 (2 SDs) and 14.0 (+2 SDs).
Answer to Question 2
ANS: B
The results for days 1 and 3 are statistically the same result (i.e., they are within the 95.5 confidence levels for this procedure and are therefore precise). The result for day 2 is clearly very significantly different, thus giving a delta check (the only possible explanation of those given here is that a patient identification error occurred and the specimen on day 2 is from a different patient). Delta checks are designed to help pick up this kind of critical error. If it had been within the 99 confidence limits, then it would have been within 3 SDs or no less than 14.0 g/dL. Because the results from day 1 and day 3 are the same, blood loss with a drop in hemoglobin cannot explain the day 2 results.