Post-Exposure Radiation Levels Are Approximately Normally Distributed, with Mean μ

Post-exposure radiation levels are approximately Normally distributed, with mean μ. The levels (in Sv) of a random sample of three trauma victims who were recently exposed are 5.5, 6.2, and 4.8 Sv. What is a 95% confidence interval for μ based on these data?

A) 5.50 ± 1.74
B) 5.50 ± 1.42
C) 5.50 ± 1.29
D) 5.50 ± 1.05