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At a local restaurant, the amount of time that customers have to wait for their food is normally distributed with a mean of 18 minutes and a standard deviation of 2 minutes. What is the probability that a randomly selected customer will have to wait less than 15 minutes, to the nearest thousandth?

At a local restaurant, the amount of time that customers have to wait for their food is normally distributed with a mean of 1818 minutes and a standard deviation of 22 minutes. What is the probability that a randomly selected customer will have to wait less than 1515 minutes, to the nearest thousandth?

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Q. At a local restaurant, the amount of time that customers have to wait for their food is normally distributed with a mean of 1818 minutes and a standard deviation of 22 minutes. What is the probability that a randomly selected customer will have to wait less than 1515 minutes, to the nearest thousandth?
  1. Calculate z-score: To find the probability, we need to calculate the z-score for 1515 minutes.\newlineZ=XμσZ = \frac{X - \mu}{\sigma}\newlineWhere XX is 1515 minutes, μ\mu is the mean (1818 minutes), and σ\sigma is the standard deviation (22 minutes).\newlineZ=15182Z = \frac{15 - 18}{2}
  2. Calculate z-score: Calculate the z-score.\newlineZ=32Z = \frac{-3}{2}\newlineZ=1.5Z = -1.5
  3. Look up in table: Now we look up the zz-score in the standard normal distribution table to find the probability. The table gives the probability that a value is less than a given zz-score.
  4. Find probability: The probability for Z=1.5Z = -1.5 is approximately 0.06680.0668.

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