Shelly has saved money since she was 10 years old. She started with $20 and then over the next 10 years the
account grew to $5000. She looked at her history of her savings and calculated he correlation coefficient as 0.85
Which of the following statements could be true? Select all that apply.
There is a strong correlation between Shelly's age and savings.
There is a weak correlation between Shelly's age and savings.
There is a positive correlation between Shelly's age and savings.
There is a negative correlation between Shelly's age and savings.

Respuesta :

There's a strong correlation between Shelly's age and savings.

There's a positive correlation between Shelly's age and savings.

Let,

Shelly's age be denoted by x

Money saved by Shelly be denoted by y

Now,

x y

10 $20

20 $5000

The sample means are represented with the symbols x(bar) and y(bar), Hence means for Shelly's age (x(bar)) and Money saved (y(bar)) are easily calculated as follows:

x(bar) = (10+20)/2

= 30/2

= 15

y(bar) = (20+5000)/2

= 5020/2

= 2510

Now,

x (xi - x(bar)) y (yi-y(bar))

10 10-15 = -5 20 20-2510 = -2490

20 20-15 = 5 5000 5000-2510 = 2490

∑[(xi - x(bar)) (yi-y(bar))] = (-5)(-2490) + (5)(2490)

= 12450 + 12450

= 24900

Now,

∑[(xi - x(bar))^2]

= (-5)^2 + 5^2

= 25 + 25

= 50

∑[(yi - y(bar))^2]

= (-2490)^2 + 2490^2

= 12400200

Hence,

√[∑[(xi - x(bar))^2] * ∑[(yi - y(bar))^2]]

= √(50 * 12400200)

= √31620510

= 17782.15

Therefore,

r = ∑[(xi - x(bar)) (yi-y(bar))] / √[∑[(xi - x(bar))^2] * ∑[(yi - y(bar))^2]]

r = 24900/17782.15

r = 1.4

But, according to given correlation coefficient (r) = 0.85

The closer r is to zero, the weaker the linear relationship.

Positive r values indicate a positive correlation, where the values of both variables tend to increase together.

Negative r values indicate a negative correlation, where the values of one variable tend to increase when the values of the other variable decrease.

Therefore, There's a strong positive correlation between Shelly's age and savings.

Learn more about correlation coefficient at : https://brainly.com/question/27226153?referrer=searchResults

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