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cdotter

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## Homework Statement

The temperature reading from a thermocouple placed in a constant-temperature medium is normally distributed with a mean μ, the actual temperature of the medium, and standard deviation σ. What would the value of σ have to be to ensure that 95% of all readings are within 0.1 degree of σ?

## The Attempt at a Solution

I looked up the solution and found the first step as P(-1.96 < x < 1.96) = 95%. This doesn't even make sense. Values of 1.96 on the normal distribution chart represent 0.975, or 97.5%. Can someone explain why I'm using these values?