Question

How much should a healthy Shetland pony weigh? Let x be the age of the pony (in months), and let y be the average weight of the pony (in kilograms).

x	3	6	12	19	24
y	60	95	140	168	173

(b) Would you say the correlation is low, moderate, or strong?

low

moderate

    strong

(c) Would you say the correlation is positive or negative?

positive

negative    

(c) Use a calculator to verify that

x = 64,

x² = 1126,

y = 636,

y² = 90,378,

and

xy = 9,774.

Compute r. (Round your answer to three decimal places.)


As x increases from 3 to 24 months, does the value of r imply that y should tend to increase or decrease? Explain your answer.

Given our value of r, y should tend to decrease as x increases.

Given our value of r, y should tend to remain constant as x increases.  

  Given our value of r, we can not draw any conclusions for the behavior of y as x increases.

Given our value of r, y should tend to increase as x increases.

Answer 1

Solution :

X	Y	XY	X^2	Y^2
3	60	180	9	3600
6	95	570	36	9025
12	140	1680	144	19600
19	168	3192	361	28224
24	173	4152	576	29929

n	5
sum(XY)	9774.00
sum(X)	64.00
sum(Y)	636.00
sum(X^2)	1126.00
sum(Y^2)	90378.00
Numerator	8166.00
Denominator	8526.57
r	0.9577
r square	0.9172
Xbar(mean)	12.8000
Ybar(mean)	127.2000
SD(X)	7.8333
SD(Y)	43.5403
b	5.3233
a	59.0613

Strong

positive

r = 0.9577

Given our value of r, y should tend to increase as x increases.