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High school girls average 95 text messages daily. Assume the population standard deviation is 15 text...

High school girls average 95 text messages daily. Assume the population standard deviation is 15 text messages.

  1. What is the probability that the sample mean is more than 90?
  2. Suppose a random sample of 100 high school girls is taken. What is the probability that the sample mean is less than 85?
  3. With the assumption about 100 girls being taken as above, what is the probability the sample mean is in between 85 and 90?
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