Question
The average weight of a group of 5 men increases by 2 kg
when a new person weighing 78 kg joins the group. What was the average weight of the group before the new person joined?Solution
Let the average weight of the original 5 men be x kg. Total weight of the original 5 men = 5x After adding the new person, the total weight = 5x + 78 New average weight = x + 2 So, 5x + 78 = 6 × (x + 2) 5x + 78 = 6x + 12 78 - 12 = x x = 66
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