InterviewSolution
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After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. The difference between the ages of the replaced and the new members is1). 2 years2). 4 years3). 8 years4). 15 years |
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Answer» Average = (sum of observation/no of observation) Let, Present age of the OLD MEMBER who is replaced = x years Present age of the new member = y years Present average of 5 members = z years Sum of present age of other 4 old member = m years Given, Number of member = 5 Present average ages of 5 members including the new member = (Sum of age of the four old member + y)/5 = (m + y)/5 Again, 3 years ago, Sum of the ages of 5 members including the old member3 years ago, = {Sum of present age of the other four old member – (4 × 3)}+ (x – 3) = (m – 12) + (x – 3) ∴ Average of 5 members 3 years ago = {(m – 12)+ (x – 3)}/5 According to the question Present average = Average 3 years ago ⇒ (m + y)/5= {(m – 12)+ (x – 3)}/5 ⇒ m + y = (m – 12) + (x – 3) ⇒ y = x – 15 ⇒ x – y = 15 years |
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