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In: Statistics and Probability

Among a random group of 36 students, the average time spent daily on telephone calls was...

Among a random group of 36 students, the average time spent daily on telephone calls was found to
be 20 minutes. Assuming that the amount of time spent daily on telephone calls by a student is a
random variable with distribution N(µ; 25), calculate the confidence interval for the mean duration,
assuming a confidence level of 0.88. How many students should be interrogated, in order to obtain a
confidence interval for the mean of length not exceeding 2, with a confidence level of 0.99?

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orchestra answered 2 years ago
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