There are approximately one billion smartphone users in the world today. In the United States the ages 13 to 55+ of smartphone users approximately follow a normal distribution with approximate mean and standard deviation of 36.9 years and 13.9 years, respectively. Use http://onlinestatbook.com/2/calculators/normal_dist.html , http://onlinestatbook.com/2/calculators/inverse_normal_dist.htmlor Excel. A) Determine the probability that a random smartphone user in the age range 13 to 55+ is between 23 and 64.7 years old. (round to 2 decimal places) B) Determine the probability that a randomly selected smartphone user in the age range 13 to 55+ is at most 50.8 years old. (round to 2 decimal places) C) Find the 80th percentile to one decimal place of this distribution. D) Find the 30th percentile to 1 decimal place. E) What is the probability that the age of a randomly selected smartphone user in the range 13 to 55+ is less than 27 years old. (2 decimal places)
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!
There are approximately one billion smartphone users in the world today. In the United States the ages 13 to 55+ of smartphone users approximately follow a
Use http://onlinestatbook.com/2/calculators/normal_dist.html , http://onlinestatbook.com/2/calculators/inverse_normal_dist.htmlor Excel.
A) Determine the
B) Determine the probability that a randomly selected smartphone user in the age range 13 to 55+ is at most 50.8 years old. (round to 2 decimal places)
C) Find the 80th percentile to one decimal place of this distribution.
D) Find the 30th percentile to 1 decimal place.
E) What is the probability that the age of a randomly selected smartphone user in the range 13 to 55+ is less than 27 years old. (2 decimal places)
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