Construct a 95% confidence interval for the mean

Reference no: EM13193519

Suppose Motorola wishes to estimate the mean talk time for its V505 camera phone before the battery must be recharged. In a random sample of 50 phones, the sample mean talk time was 347 minutes.

a) Why can we say the sampling distribution of the sample mean is approximately normal?

b) Construct a 95% confidence interval for the mean talk time for all V505 camera phones, assuming that sigma is 34 minutes. Interpret this interval.

c) How many phones would Motorola need to test to estimate the mean talk time for all V505 camera phones within 5 minutes with 95% confidence?

Reference no: EM13193519

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