TIPS

1. To calculate the average, the units for all the items must be the same
   


2. Example:
   The average score of five pupils in a Mathematics test is 82 marks. If four of the pupils’ marks are 75, 80, 67 and 97, how many marks does the fifth pupil score? SolutionTotal item values
   = Average x Number of items
   = 82 x 5
   = 410
   Total of four pupils’s marks
   = 75 + 80 + 67 + 97
   = 319
   So, the fifth pupil’s marks
   = 410 – 319
   = 91

COMMON MISTAKES

1. What is the average of 2 kg, 0.5 kg, 1.3 kg and 120 g?
   Incorrect :
   
   Correct: