WAEC - Mathematics (2017 - No. 22)
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
10.1 years
9.3 years
8.7 years
8 . 3 years
คำอธิบาย
x = 10 ; 10 = \(\frac{x}{25}\)
x = 250
x = \(\frac{250 + 12.4}{26}\)
x = 10.09
x = 10.1 years