The average age of a group of 25 girls is 10year. If one girl, aged 12 years and 4 months joins the group, find the new average age of the group

  • A 10.1 years
  • B 9.3 years
  • C 8.7 years
  • D 8 . 3 years
waec 2017mathematics

The correct answer is A. 10.1 years

x = 10 ; 10 = \(\frac{x}{25}\)

x = 250

x = \(\frac{250 + 12.4}{26}\)

x = 10.09

x = 10.1 years

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