Question

hii...here is a challenge for u.........

Answer 1

Let the Total Number of Students in the Class be : S

Given : The Average Age of Students in the Class : 15.8 years

⇒ $\dfrac{Sum\;of\;Age\;of\;'S'\;Number\;of\;Students}{S} = 15.8$

⇒ Sum of Age of 'S' Number of Students = 15.8 × S

Let the Number of Boys in the Class be : B

Given : The Average Age of Boys in the Class : 16.4 years

⇒ $\dfrac{Sum\;of\;Age\;of\;'B'\;Number\;of\;Boys}{B} = 16.4$

⇒ Sum of Age of 'B' Number of Boys = 16.4 × B

Let the Number of Girls in the Class be : G

Given : The Average Age of Girls in the Class : 15.4 years

⇒ $\dfrac{Sum\;of\;Age\;of\;'G'\;Number\;of\;Girls}{G} = 15.4$

⇒ Sum of Age of 'G' Number of Girls = 15.4 × G

But : Sum of Age of 'S' Number of Students = Sum of Age of 'B' Number of Boys + Sum of Age of 'G' Number of Girls

⇒ (15.8 × S) = (16.4 × B) + (15.4 × G)

But : S = B + G

⇒ 15.8(B + G) = 16.4(B) + 15.4(G)

⇒ 15.8(B) + 15.8(G) = 16.4(B) + 15.4(G)

⇒ 16.4(B) - 15.8(B) = 15.8(G) - 15.4(G)

⇒ 0.6(B) = 0.4(G)

⇒ $\dfrac{B}{G} = \dfrac{0.4}{0.6} = \dfrac{4}{6} = \dfrac{2}{3}$

⇒ The Ratio of Number of Boys to the Number of Girls is 2 : 3