In a class average age of 15 boys is 11. If 5 boys each of age 9 years are added, what would be the new average?

10.5 years 10 Years 20 Years 23 Years

10.5 years

Total age of boys in a class = 15 x 11 = 165 Total age after adding 5 new boys = 165 + 9 x 5 = 210 New average = \(\frac{210 }{ \text{15 + 5}}\) New average = \(\frac{210 }{ 20}\) New average = 10.5