Given : Marks of 12 students in a unit test are given as 4, 21, 13, 17, 5, 9, 10, 20, 19, 12, 20, 14.
Arrange the data from ascending to descending,
4, 5, 9, 10, 12, 13, 14, 17, 19, 20, 20, 21
Assumed mean is almost the median of the data.
Median of 12 terms is
\(M = \frac{6th + 7th}{2}\)
\(M = \frac{13+14}{2}\)
\(M = \frac{27}{2}\)
M = 13.5 is the assumed mean.
Arithmetic mean is defined as the sum of observation upon total number of observation.
Therefore, The arithmetic mean is closest to assumed mean but not equal.
