If the variance of the water temperature in a lake is 28 degrees how many days should the researcher select to measure the temperature to estimate the true mean within 3 degrees with 90% confidence? Round the intermediate calculations to two decimal places and round up your final answer to the next whole number.
The researcher needs at least how many day?
Answer:
Given Data
variance = =
standard deviation = 6
= 5.29
Margin of error E =
At 90% confidence level the Z is
= 1 - 90%
= 1 -0.90
= 0.10
= 0.10/2
= 0.05
Sample size = n =
=
= 8.414
Sample size = n = 9
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