The average age of a group of 25 girls is 10 years. If one girl aged 12 years and 4 months joins the group, find, correct to one decimal place, the new average age of the group.
12yrs, 4 mths = 12 + 1/3 yrs = 37/3 yrs
25 (10) + 37/3 787/3
_____________ = ______ ≈ 10.1 yrs = new avg age
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