If the frequency distribution is from a sample, determine the value of: a. the 65th percentile; b. the 4th decile; c. the rst quartile; d. the median; e. percentile rank of a value of 15. E E E E Remember. to answer these questions, you will need the formula: where: P: = the value at the xth percentile; x = the number of the desired percentile; n = the total number of observations; i = the size of the class interval; Lx = the lower limit of the class containing the xth percentile; fx = the number of observations in the class containing the xth percentile; ft: = the cumulative frequencies below the class containing the xth percentile