Question

If n = 16, ¯xx¯ = 30, and s = 7, construct a confidence interval
at a 80% confidence level. Assume the data came from a normally
distributed population. Give your answers to three decimal
places.

< μμ <

Answer #1

As sample size is small (n=16) and population standard deviation is not given , also data comes from normal population , we use t distribution to find the confidence interval for mean

The 80% confidence interval for mean is

degrees of freedom = n-1 = 16-1=15

For 80% confidence ( =0.20) with df =15 , critical value of t is

tc =1.341 (from t table)

Thus, 80% confidence interval for mean is

= (27.653 , 32.347 )

Answer is : **27.653 <
< 32.347**

If n = 28, x = 44, and s = 11, construct a confidence interval
at a 80% confidence level. Assume the data came from a normally
distributed population. Give your answers to three decimal places.
< μμ <

If n=21, ¯xx¯(x-bar)=44, and s=17, construct a confidence
interval at a 98% confidence level. Assume the data came from a
normally distributed population.
Give your answers to one decimal place.
< μμ <

If n=30, ¯xx¯(x-bar)=49, and s=10, construct a confidence
interval at a 90% confidence level. Assume the data came from a
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Give your answers to one decimal place.
_______< ? < ________

If n=19, ¯xx¯=34, and s=5, construct a confidence interval at a
80% confidence level. Assume the data came from a normally
distributed population.
Give your answers to one decimal place.
Enter answer in interval notation
(____,____)

If n = 17, ¯ x = 42, and s = 20, construct a confidence interval
at a 90% confidence level. Assume the data came from a normally
distributed population. Give your answers to three decimal
places.
? < μμ < ?

1) If n=19, ¯xx¯(x-bar)=33, and s=18, construct a confidence
interval at a 80% confidence level. Assume the data came from a
normally distributed population.
Give your answers to one decimal place.
< μμ <
2) You measure 48 backpacks' weights, and find they have a mean
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the true population mean backpack weight.
Give your answers as decimals, to two...

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interval at a 80% confidence level. Assume the data came from a
normally distributed population.
Give your answers to one decimal place.
< μμ <
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Give your answer...

If n=15, ¯xx¯(x-bar)=33, and s=10, construct a confidence
interval at a 98% confidence level. Assume the data came from a
normally distributed population.
Give your answers to one decimal place.

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interval at a 95% confidence level. Assume the data came from a
normally distributed population.
Give your answers to one decimal place.
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Construct a confidence interval at a 90% confidence level.
Give your answers to one decimal place....

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a 90% confidence level. Assume the data came from a normally
distributed population.
Give your answers to one decimal place.
____ < μμ < ____

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