Question
The average age of a group of seven children is 10
years. From the group, two children, whose ages were 5 years more and 3 years more than the average age, left. Three new children, whose average age is 4 years more than the given average age, join the group. Find the new average age.Solution
Initial sum of the ages of 7 children = 10 x 7 = 70 years Ages of the children leaving: 10 + 5 = 15 years and 10 + 3 = 13 years, Sum of the children leaving =15+ 13 = 28 years Sum of the ages after two children left = 70 - 28 = 42 years Sum of the ages of 3 new children = 10 + 4 x 3 = 42 years Total sum of the ages with new children = 42 + 42 = 84 years Number of children now = 7 – 2 + 3 = 8 New average age = 84/8 = 10.5 years
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