1.   The mean and standard deviation of a set of data are 30.5 and 13.8, respectively. Assume that the data are normally distributed. Name the interval about the mean in which about 68.3% of the data are located.
    A. 30.5 ± 13.8 B. 13.8 ± 1.0
    C. 30.5 ± 6.9 D. 30.5 ± 1.0
    Hint

  2.   Given the partial table below, identify the upper and lower limits of an interval about the mean within which 45% of the values of a set of data can be found if the mean is 30.5 and the standard deviation is 13.8. Assume the data are normally distributed.
   
    A. 22.22-38.78 B. 5.5-22.1
    C. 26.3-34.7 D. 9.6-18.0
    Hint

  3.   Using the partial table below, what percent of the data is between 40 and 50 if the mean is 30.5 and the standard deviation is 13.8? Assume the data are normally distributed.
   
    A. 24.2% B. 32.2%
    C. 16.1% D. 12.1%
    Hint

  4.   The mean of a set of normally distributed data is 65 and the standard deviation is 13. Using the partial table below, what percent of the data is between 40 and 56?
   
    A. 21.40% B. 42.70%
    C. 30.50% D. 26.80%
    Hint

  5.   The mean of a set of normally distributed data is 65 and the standard deviation is 13. Find the value that defines the 75th percentile.
    A. 75.8 B. 75
    C. 72.6 D. 74.1
    Hint