The mean age of 5 boys is equal to 9.8. Furthermore, the mean age of 15 girls is 10.2. The mean age of the 20 children together is equal to?
+37158 Sum of boys /5 = 9.8 Sum of girls/15 = 10.2
Sb = 5* 9.8 = 49 Sg = 153
(49 + 153)/ (5+15) = 10.1 years
