To calculate the standard deviation of those numbers: 1  1. 2  Work out the Mean (the simple average of the numbers). 3  2. Then for each number: subtract the Mean and square the result.4  3. Then work out the mean of those squared differences.5  4. Take the square root of that and we are done!o calculate the standard deviation of those numbers: 1  1. 2  Work out the Mean (the simple average of the numbers). 3  2. Then for each number: subtract the Mean and square the result.
FBF = Flashback Friday. #FBF is an acronym primarily used on Instagram, Facebook, Twitter, and Tumblr that stands for Flashback Friday. Users typically use the tag on photos of moments in their past, like last yearâs vacation or a childhood friend.
Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a system during operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a system. The terms is used in both plant and equipment maintenance contexts. The MTBF is typically part of a model that assumes the failed system is immediately repaired (mean time to repair, or MTTR), as a part of a renewal process.