| An Example – cont. |
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| q | In an experiment, forty measurements of air temperature
were made. |
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| The mean and standard deviation of the sample are: |
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x = 18.41°C
and s =
0.6283°C. |
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| Question 2: |
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| How many
measurements would be required to reduce the 95% |
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| confidence interval for the population mean to (x-0.1)°C
to (x+0.1)°C? |
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| Answer: |
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| We want to have Z95% * s
/ (N)0.5 = 0.1 °C |
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| We already know Z95%
= 1.96 and s = 0.6283°C |
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| è N = (1.96´0.6283/0.1)2 = 152 |
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