# Statistics question

Anonymous
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Question description

Attached below is 20 questions for my elementary to statistics please help any way you can as this stuff doesnβt make sense to me. thank you!

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uoscar
School: Carnegie Mellon University

Please, use this attachment. I made some corrections to the solution of Q9 and Q10.Please give me feedback.

Q1: What is the predictor variable?
Answer: The predictor variable is number of Hours Studied.

Q2: What is the criterion variable?
Answer: The criterion variable is Score on Quiz.

Q3: What is the covariance?
Solution:
COV(X, Y) = SXY =
πΜ =

β π₯ 11
=
= 2.75
π
4

β΄ SXY =

πΜ =

β (ππ β πΜ)(ππ β πΜ)
πβ1

β π¦ 22
=
= 5.50
π
4

(1 β 2.75)(3 β 5.50) + (2 β 2.75)(5 β 5.50) + (3 β 2.75)(5 β 5.50) + (5 β 2.75)(9 β 5.50)
nβ1

SXY =

(β1.75)(β2.5) + (β0.75)(β0.5) + (0.25)(β0.5) + (2.25)(3.5)
4β1

SXY =

4.375 + 0.375 β 0.125 + 7.875 12.5
=
= 4.1667
3
3

Alternatively:
COV(X, Y) =

β ππ β πΜ β π β πΜ β π + ππΜπΜ 73 β (5.5)(11) β 2.75(22) + 4(2.75)(5.5) 12.5
=
=
πβ1
4β1
3

Q4: What is the standard deviation of the predictor variable?
Solution
The predictor variable is X (i.e. the number of hours studied). The standard deviation is given by:
Μ β π + ππ
Μ2
β (ππ β πΜ)2
β π2 β 2π
β
ππ = β
=
πβ1
πβ1
39 β 2(2.75)(11) + 4(2.752 )
8.75
β΄ ππ = β
=β
= 1.7078
4β1
3
Answer: The standard deviation of the predictor variable is 1.7078
Q5: What is the standard deviation of the criterion variable?
Solution
The criterion variable is Y (i.e. Score on Quiz). The standard deviation is given by:
β (ππ β πΜ)2
β π2 β 2πΜ β π + ππΜ 2
β
β
ππ =
=
πβ1
πβ1
140 β 2(5.50)(22) + 4(5.502 )
19
β
β΄ ππ =
= β = 2.5166
4β1
3
Answer: The standard deviation of the criterion variable is 2.5166
Q6: What is the Pearsonβs r value?
Solution
The Pearsonβs correlation coefficient, r is given by:
π=

π β π₯π¦ β β π₯ β π¦
β[π β π₯ 2 β (β π₯)2 ][π β π¦ 2 β (β π¦)2 ]

Alternatively, r can be computed from the standard deviation as:
π=
β΄π=

πππ
ππ β ππ

4.1667
= 0.9695
1.7078 Γ 2.5166

Answer: The Pearsonβs r value is 0.9695

Q7: What is the best interpretation of your Pearsonβs correlation in Q6?
(A) As βhours studiedβ goes up, there is a corresponding increase in βscore on quiz)

Q8: The strength of the above relationship is considered?

Part B** Compute the regres...

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Anonymous
Awesome! Exactly what I wanted.

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