Question by warrior: What is the probability that the sample of kindergarten children has a mean height of less than 40.3 inches?
Kindergarten children have heights that are approximately normally distributed about a mean of 39.6 inches and a standard deviation of 1.6 inches. If a random sample of 28 is taken, what is the probability that the sample of kindergarten children has a mean height of less than 40.3 inches?
i tried (40.39.6)/(1.6/√28) = 2.3155 and that is my z-score.. correct? so then the probability should be .4896 right? wells its not…. what am i doing wrong here?
Best answer:
Answer by Gerry
For one thing, a simple look at the fact that 4.3 > 39.6 should let you know that the answer must be larger than 1/2 so you should notice that your answer is incorrect.
The value 40.3 inches is (40.3 – 39.6) / 1.6 = .7 / 1.6 = .4375 standard deviations from the mean.
The probability that the mean height is less than 40.3 inches is .6991
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