Tricks to find Mean, Median, Mode

Tricks to find Mean, Median, Mode


1. Mean (Average) Trick


Formula


Mean = Sum of all observations / Number of observations


Quick Trick


·   Add fast using pair method
Ex: 12, 18, 20, 10
Pair them: (12+18) = 30, (20+10) = 30


Mean = 30+30 / 4 = 60 / 4 = 15


2. Median Trick


1st: Odd number of terms


Median = Middle value


Arrange in ascending order first


Ex: 5, 2, 9 → Arrange: 2, 5, 9 → Median = 5


2nd : Even number of terms


Median = Middle 2 values/2


Ex: 4, 8, 6, 2 → Arrange: 2, 4, 6, 8→ Median = 4+6/2 = 5


3. Mode Trick


Mode = Number that appears the most


Ex: 3, 7, 3, 2, 9, 3
Mode = 3 (repeat most)


If two repeat same times → Bimodal


Ex: 4, 6, 4, 8, 8
Mode = 4 & 8 (both repeat)


Special Quick Tips - By Points



  • Mean → Pair numbers to add quickly

  • Median → Always arrange in ascending order first

  • Mode → Find the number that repeats the most

  • If no number repeats → Mode = No mode

  • If 2 numbers repeat equally → Bimodal

  • If 3 numbers repeat equally → Trimodal


Super Quick Revision



  • Mean → total ÷ count

  • Median → middle (after arranging)

  • Mode → most repeated


Q. A dataset consists of x, 2x, 3x, and 4x. If the mean is 12.5, what is the median 


Soln


Given:


Dataset: x, 2x, 3x, 4x
Mean = 12.5


Use mean to find x


Mean = x+2x+3x+4x / 4 =10x/4 = 2.5x


              2.5x = 12.5


                   x = 12.5/2.5 = 5


Substitute values in the dataset X = 5


So the dataset becomes: 5,10,15,20


Find the Median


Since there are 4 numbers (even count):


Median = 2nd value+3rd value/2 =10+15/2 = 25/2 =12.5


Ans:12.5