X = girls
Y = boys
X + y = 428
I don’t really know what this means
We know the following:
Cylinder volume: V₁ = π r² h
Ball (sphere) volume:V₂ =

π r³
where:
V - volume
r - radius of base of cylinder and diameter of ball
h - height of cylinder.
R = 13 cm ⇒ r = 13 ÷ 2 = 6.5
π = 3.14
a) Since balls touch all sides of cylinder (as shown in image), it can be concluded that height of cylinder is equal to sum of diameters of 3 balls and that radius of base of cylinder is equal to radius of ball:
h = 3 × r = 3 × 13 cm = 39 cm
r = 6.5 cm
So,
V₁ = <span>π r² h
</span><span>V₁ = </span>3.14 × (6.5 cm)² × 39 cm
V₁ = 5,173.9 cm³
b. The total volume of three balls is the sum of volumes of each ball:
Vₐ = 3 × <span>V₂
</span>Vₐ = 3 × <span>

π r³
</span>Vₐ = 3 ×

3.14<span> (6.5 cm)³</span>
Vₐ = 3,449.3 cm³
c. Percentage of the volume of the container occupied by three balls ould be expressed as ratio of volume of three balls and volume of cylinder:
V =

×100
V =

×100
V = 0.6666 ×100
V = 66.66%
So you would take 3x1+2 that gives you 5 and you would keep the same denominator and so that would give you 5/3 then do the same to the other side which would give you 5/4 then you would times it and that would give you 2 1/12
If you're trying to say what's 90% of 63, you divide 63 by 10 which is 6.3 then times by 9 which is 56.7