Question

in a school there are 450pupils.Boys & girls ratio 4:5. some new pupil were admitted and number of boys increased by 25 and new ratio increased to 9:13. calculated the new girls admitted​

Answer 1

Step-by-step explanation:

• 450 is divided between boys and girls

so

(Boys+Girls)=450

given

(Boys/girls)=4/5

therefore

Boys=4/5of Girls

now

Boys+girls=450

4/5(girls)+girls=450

9/5(girls)=450

girls=250

and boys =200

now

• new ratio is given 9/13

let new girls admitted is x

new ratio will be

(Boys+20)/(girls+x) =9/13

we will put boys =200 & girls =250

therefore

(200+25)/(250+x)=9/13

225/(250+x)=9/13

225×13=9×(250+x)

2925=2250+9x

2925-2250=9x

675=9x

675/9=x

75=x

therefore

new girls added in school is 75