1. In order to estimate ** the
average time **spent on the computer terminals per student at

a university, data were collected for a sample of
** 81 business students**
over a one week

period. Assume ** the
population standard deviation** is

* the margin
of error* is approximately

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2. It is known that the variance of a population
equals ** 1936**. A random
sample of

has been taken from the population. There is a 0.95 probability that the sample mean

will provide ** a
margin of error **of

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3. It is known that ** the
population variance** equals

**the **** sample
size** that needs to be taken
if the desired margin of error is

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4. A researcher is interested in determining ** the
average number of years **employees of a

company stay with
the company. If past information shows
** a standard deviation of 7 months**,

* what size *sample
should be taken so that at 95% confidence the margin of error will be

**2 months or
less**

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5. If ** the standard deviation**
of the lifetime of washing machines is estimated to be

how large a sample must be taken in order to be ** 97%**
confident that

* not exceed 50 hours*?

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