Two independent measurements are made of the lifetime of a charmed strange meson. Each measurement has a standard deviation of 7 ×10-15 seconds. The lifetime of the meson is estimated by averaging the two measurements. What is the standard deviation of this estimate?

Solution:

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Two independent measurements are made of a charmed strange meson. Each measurements has a standard deviation 7 10^ -15 seconds. The lifetime of the meson is estimated by averaging the two measurements. We have to find standard deviation of this estimate.