Approximate the median of the frequency distribution in Problem 3. Temperature (F) ....Frequency 61-64 ......... 31 65-67 ......... 67 68-69 .......198 70 .........195 71-72 ........120

Approximate the median of the frequency distribution in Problem 3.

Temperature (°F) ....Frequency

61-64 ......... 31

65-67 ......... 67

68-69 .......198

70 .........195

71-72 ........120

73-76 ......... 89

77-80 ......... 50

Use the following steps to approximate the median from grouped data.

Approximating the Median from Grouped Data

Step I Construct a cumulative frequency distribution.
Step 2 Identify the class in which the median lies. Remember, the median can be obtained by determining the observation that lies in the middle.

Step 3 Interpolate the median using the formula

where
L is the lower class limit of the class containing the median
n is the number of data values in the frequency distribution
CF is the cumulative frequency of the class immediately preceding the class containing the median
f is the frequency of the median class
i is the class width of the class containing the median

rt - CF Median = M = L + (i)