Assume that blood pressure readings are normally distributed with u = 124 and o = 9. A researcher wishes to select people for a study but wants to exclude the top and bottom 8 percent. What would be the upper and lower readings to qualify people to participate in the study?
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!
Consider X be the random variable representing the blood pressure readings. X follows normal distribution with mean 124 and standard deviation 9
Let upper and lower readings be "a" and "b" respectively.
The percentage of people having blood pressure less than "a" is 8%
The percentage of people having blood pressure greater than "b" is 8%
This implies that the percentage of people having blood pressure less than "b" is 92% (1-8% )
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