The 14th 0ne please answer fast

Dear Student,
Solution)
Let the number of boys and girls be x and y respectively.

As, we know that,
Sum of observations = Mean × Number of observations 

Given, Mean marks of boys in the examination = 70

∴ Sum of marks obtained by boys in the examination
= 70 × x
= 70x 

Given, Mean marks of girls in the examination = 73

∴ Sum of marks obtained by girls in the examination
= 73 × y
= 73y 

Given, Mean marks of all students in the examination = 71

∴ Sum of marks obtained by all students in the examination
= 71 (x + y)

Sum of marks obtained by all students in the examination 
= Sum of marks obtained by boys in the examination +
   Sum of marks obtained by girls in the examination

∴ 71 (x + y) = 70x + 73y

⇒ 71x + 71y = 70x + 73y

⇒ 71x – 70x = 73y – 71y

⇒ x = 2y
$\Rightarrow \frac{x}{y}=\frac{2}{1}$

⇒ x : y = 2:1

Thus, the ratio of number of boys to the number of girls is 2 :1

Regards!