G8.7

Repeated lab measurements. A laboratory kit states that the standard deviation of its results can be expected to vary with sigma=1 unit. A lab technician takes four measurements using this kit.

1. What is the value of the standard deviation of the xbar of the four measurements taken with this kit?
2. Explain to a layperson the advantage of reporting the average of four measurements rather than using a single measurement.

1. How many times must we repeat the measurement before we obtain a standard deviation of 0.2 units?