If the frequency distribution is from a sample, determine the value of: a. the 65th percentile; b. the 4th decile; c. the first quartile; d. the median; e. percentile rank of a value of 15. Class Interval Frequency 0 to under 10 4 10 to under 20 6 20 to under 30 10 30 to under 40 8 40 to under 50 6 50 to under 60 4 60 to under 70 2 Remember, to answer these questions, you will need the formula: RX PX = L + (i ) 100 where: Px = 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; [fc = the cumulative frequencies below the class containing the xth percentile