A manufacturer of calculator batrries claims that the mean length of life for its battry is 500 operating hours. Suppose the standard deviation of the length of life is known to be 25 operating hours,and the distribution of life length is symmetric and mound-shaped. Approxiamately what percentage of the manufacturer'sbattries will last less than 525 hours?
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
A manufacturer of calculator batrries claims that the mean length of life for its battry is 500 operating hours. Suppose the standard deviation of the length of life is known to be 25 operating hours,and the distribution of life length is symmetric and mound-shaped. Approxiamately what percentage of the manufacturer'sbattries will last less than 525 hours?
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