Question

25 boys collected average rupees75 for picnic, 20 boys collected average rupees 80. find the average collection of the boys
options:
1) 40.44
2) 66.44
3)59.44
4) 90.44​

Answer 1

Answer:

⇒ Let boys be x, then girls be 60−x

⇒ Contribution by boys =x(60−x)

⇒ Contribution by girls =(60−x)x

⇒ Total money collected =Rs.1600

∴ 60x−x

2

+60x−x

2

=1600

⇒ −2x

2

+120x−1600=0

⇒ −2(x

2

−60x+800)=0

⇒ x

2

−60x+800=0

⇒ x

2

−40x−20x+800=0

⇒ x(x−40)−20(x−40)=0

⇒ (x−40)(x−20)=0

∴ x=40 and x=20

∴ Number of boys in class are 20 or 40