The standard normal tables show that the area below Z= -1.82 is equal to 0.0344. A population of office workers commuting by bus to a central business district location has trips on a particular day with an average of 45 minutes and a standard deviation of 17.5 minutes. It is found that there is a 3.44% chance that a sample from this population has a journey time less than 42 minutes. What is the sample size? Give you answer correct to the closest integer. Answer:
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!
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