Friday, October 2, 2015

Suppose you know that the heights of elementary school students in southern Kenya follow a normal probability distribution with a mean of 40.1 inches and a (population) standard deviation of 2.2 inches.

What is the probability that an elementary school student in southern Kenya is greater than or equal to 41.3 inches tall? (Round to the nearest percent.)

  z score is (x - mean)/standard deviation

  so (41.3 - 40.1)/2.2 
  • and look up that on a standard normal distribution chart
  • z-chart
  • to that value for z (.55) is .7088
  •   that is the probability of LESS than z(.55) 
So you take 1- .7088 to get .2912

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