A simple random sample of size \( n \) is drawn from a population that is normally distributed. The sample mean, \( \bar{x} \), is found to be 103 , and the sample standard deviation, s , is found to be 12 . (a) Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . (b) Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 14. (c) Construct a \( 90 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . (d) Should the confidence intervals in parts (a)-(c) have been computed if the population had not been normally distributed? Compare the results to those obtained in part (a). How does decreasing the level of confidence affect the size of the margin of error, E? B. As the level of confidence decreases, the size of the interval decreases. B. As the level of confidence decreases, the size of the interval stays the same.

5 The distribution of resting pulse rates of a sample of 2000 20-year-old men is approximately normal, with a mean of 66 beats/minute and a standard deviation of 4 beats/minute. a What percentage of these men have pulse rates of: i higher than 66 ? ii between 66 and 70 ? iii between 62 and 74 ? b Approximately how many of this sample of 2000 men have pulse rates between 54 and 78 beats/minute?

The distribution of heights of 19 -year-old women is approximately normal, with a mean of 170 cm and a standard deviation of 5 cm . a What percentage of these women have heights: i between 155 and 185 cm ? ii greater than 180 cm ? iii between 160 and 175 cm ? b In a sample of 5000 of these women, approximately how many have heights greater than 175 cm ?

Cite as características que um bom diagrama de dispersão deve ter para facilitar a interpretação dos dados.

Which of the following is/are part of descriptive statistics? central tendency. variability. linear regression. correlation. all of the above.

24. What is the \( y \)-intercept of the trend line equation, and what does it mean in the context of the situation?