The following data represents the age(in weeks) at which babies first crawl base

Question

The following data represents the age(in weeks) at which babies first crawl based on a survey of 12 mothers. 52, 30,44,35, 47, 37, 56, 26, 30, 54, 35, 52, Mean = 41.5 weeks Standard deviation 10.59 a) Because the sample size is small we must verify that the data came from a population that is normally distributed and that the sample size does not contain any outliers. Are the conditions for constructing a confidence interval about the mean satisfied. A) yes, the population is normally distributed and the sample does not contain outliers B) No the population is not normally distributed C) No the sample contains an outlier b) Construct a 95% confidence interval for the mean age at which a baby first crawls. Select the correct choice below nd fill in any amnswer boxes in your choice. A)______ and ______, B) A 95% confidence interval can not be constructed c)What could be done to increase the accuracy of the interval with out changing the level of confidence? A) Increase the sample size B) Either increase or decrease the sample size C) decrease the sample size D) Nothing can be done.

Explanation / Answer

a) Because the sample size is small we must verify that the data came from a population that is normally distributed and that the sample size does not contain any outliers. Are the conditions for constructing a confidence interval about the mean satisfied.

A) yes, the population is normally distributed and the sample does not contain outliers

b) Construct a 95% confidence interval for the mean age at which a baby first crawls. Select the correct choice below nd fill in any amnswer boxes in your choice.

alpha = 0.05

alpha /2 = 0.025

df = 12-1=11

t = 2.201

Mean = 41.5 weeks Standard deviation 10.59

I: 41.5 +/- 2.201 * 10.59 / srqt(12)

41.5 +/- 6.7286

34.7714 < miu < 48.2286

)What could be done to increase the accuracy of the interval with out changing the level of confidence?

Increase the sample size

increasing the sample size we are going to have a standard error more lower

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