Question

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 1

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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