Question

A random sample of the number of students per class at Citrus College is shown below. (6 points)

Class Boundaries	Frequency
4.5 - 9.5	11
9.5 - 14.5	18
14.5 - 19.5	7
19.5 - 24.5	3

1. Find the modal class for the data.

Modal Class is Select an answer 4.5 - 9.5 9.5 - 14.5 14.5 - 19.5 19.5 - 24.5   

2. What formula will you use for the mean?

• ¯x=∑w⋅x∑wx¯=∑w⋅x∑w
• μ=∑xNμ=∑xN
• ¯x=∑xnx¯=∑xn
• ¯x=∑f⋅xm∑fx¯=∑f⋅xm∑f

3. What formula will you use for the variance?

• s2=n(∑f⋅x2m)−(∑f⋅xm)2n(n−1)s2=n(∑f⋅xm2)-(∑f⋅xm)2n(n-1)
• s= ⎷n(∑f⋅x2m)−(∑f⋅xm)2n(n−1)s=n(∑f⋅xm2)-(∑f⋅xm)2n(n-1)
• σ=√∑(x−μ)2Nσ=∑(x-μ)2N
• s=√∑(x−¯x)2n−1s=∑(x-x¯)2n-1
• s2=∑(x−¯x)2n−1s2=∑(x-x¯)2n-1
• σ2=∑(x−μ)2Nσ2=∑(x-μ)2N

4. Please explain how you determined the correct formula for mean and variance?

• A cumulative frequency distribution is provided.
• A group frequency distribution is provided.
• Raw data of a sample is provided.
• Raw data of a population is provided.
• Asks for the weighted mean

5. Find the mean, variance and standard deviation.

Class Boundaries	Frequency (Select an answer N w xₘ f·xₘ n-1 n(n-1) n f f·xₘ²  )	Midpoints (Select an answer ∑f ∑f·xₘ² N xₘ n(n-1) n ∑f·xₘ n-1 ∑w  )	Select an answer f·xₘ² f·xₘ x - x̄ w w·x (x - x̄)² x - μ (x - μ)²	Select an answer w·x w (x - x̄)² x - μ x - x̄ f·xₘ (x - μ)² f·xₘ²
4.5 - 9.5	11
9.5 - 14.5	18
14.5 - 19.5	7
19.5 - 24.5	3
	Select an answer ∑(x - x̄)² ∑w·x ∑(x - μ) ∑w ∑f ∑f·xₘ ∑(x - μ)² ∑f·xₘ² ∑(x - x̄)  =		Select an answer ∑(x - x̄)² ∑w·x ∑f·xₘ ∑(x - μ)² ∑(x - x̄) ∑f·xₘ² ∑w ∑(x - μ) =	Select an answer ∑(x - μ)² ∑w·x ∑(x - x̄) ∑f·xₘ² ∑f·xₘ ∑w ∑(x - μ) ∑(x - x̄)² =

			Round to Two Decimal Places
Mean:	Select an answer Mode x̄ σ² MD σ MR s² s μ	≈	students
			Round to Two Decimal Places
Variance:	Select an answer μ s x̄ σ MD s² MR Mode σ²	≈	students2
			Round to Two Decimal Places
Standard Deviation:	Select an answer MR s² Mode s x̄ MD μ σ σ²	≈	students

6. What will be best for center (Mean or Median)? Please explain.

• Mean because it is bell-shaped
• Median because it is skewed right
• Mean because it is skewed left
• Mean because it is skewed right
• Median because it is skewed left

Answer 1