The average weight of a certain number of persons in a group was 75.5 kg. Later on, 4 persons weighing 72.6 kg. 74 kg, 73.4 kg and 70 kg joined the group. As a result, the average weight of all persons in the group reduced by 500g. The number of persons in the group, initially, was:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 20.
Let the number of people be x.
The initial average weight of people = 75.5
Sum of the initial weights = 75.5x
72.6 kg. 74 kg, 73.4 kg, and 70 kg were added and the average decreased to 75.
Sum of weights of these 4 people = 72.6 + 74 + 73.4 + 70 = 290 kg
Total sum = 75.5x + 290
Average = Sum of all the weights/Total people
Average = (75.5x + 290)/(x + 4) = (75.5x + 290)/(x + 4) = 75
75.5x + 290 = 75x + 300
0.5x = 10
x = 20 people