6:2:3:4
for every 6 pairs of wedges she owns 2 Stillettos, 3 sneakers and 4 sandals
18/6 =3
3*2 =6 stilettos
3*3 = 9 sneakers
3*4 =12 sandals
18 + 6 + 9 + 12 = 45 pairs of shoes
We know that 5x-3x =2x
So x(5x-3x)=x×2x
=(2x)^2
=4x^2
Which is given as 18.
X^2=18÷4
=4.5
So x=root over 4.5
Which is approximately 2.25
Answer B.
∑fx=1637,∑fx
2
=127663,∑f=21
x
ˉ
=Mean=
∑t
∑fx
=77.95
σ
2
=
∑f
∑fx
2
−(
x
ˉ
)
2
=
21
127663
−(77.95)
2
=2.987
σ=1.728