Example: A random sample of 25 patients received the new migraine medication. Their relief times had mean of 7.5 minutes

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Example: A random sample of 25 patients received the new
migraine medication. Their relief
times had mean of 7.5 minutes and standard deviation of 2.1
minutes. A random sample of 30
patients received the standard medication, and their relief times
had mean 14.3 minutes with
standard deviation of 3.2 minutes. Assume that relief times for
both medications are normally
distributed. Find the common sample size such that the 95%
confidence interval for the difference
in mean relief times for the new and the standard medications has
the width of at most 2.