The average age of 12 boys is 15 years and the average age of 18 girls is 12 years. What is the combined average age of the boys and girls, taken together?

13.2

Sum of age of 12 boys is = 12 × 15 = 180 years

Sum of age of 18 girls is = 18 × 12 = 216 years

Combined Average age of boys and girls = \(\frac{180 + 216 }{12 + 18 }\)

= \(\frac{396 }{30 }\) = 13.2