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Discussion

  1. The average age of a group of 10 friends is 15 yr. If one friend leaves the group, the average becomes 16 yr. Find the age of the friend who left the group.
    1. 5 yr
    2. 4 yr
    3. 6 yr
    4. None of these
  1. Correct Option: C

    Age of friend left = Previous average of the age - Number of persons present x Increase in average age
    = 15 - ( 10-1 ) x ( 16-15 )
    = 15- 9 x 1
    = 15 - 9 = 6yr


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