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The scores for the mathematics portion of a standardized test are normally distributed with a mean of 514 points and a standard deviation of 117 points. What is the probability that a randomly selected student has a score of 631 points or less on the test? Use the standard normal distribution and a calculator or table to estimate the probability.

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Respuesta :

Mindaka
First, find the z-score:

z = (value - mean) / sdev
  = (631 - 514) / 117
  = 1

Now, look at a standard normal table to find P(z ≤ 1) = .84134

Therefore, we have a probability of about 84% to find a randomly selected student with a score of 631 points or less.