The average weight of 49 students in a class is 39 kg. Seven of them whose average weight is 40 kg left the class and other seven students whose average weight is 54 kg joined the class. What is the new average weight (in kg) of the class?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 41.
We know that,
Average = Sum of observations/Number of observations
Now, according to the question
Total weight of class before students left = 49 × 39 = 1911 Kg
Total weight of 7 students leaving = 7 × 40 = 280 Kg
Total weight of 7 new students = 7 × 54 = 378 Kg
The total weight of class after replacement = 1911 - 280 + 378 = 2009
Now,
The average weight of the class after replacement = 2009/49 = 41