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Suppose the correlation between height and weight for adults is [tex]$0.40$[/tex]. What proportion (or percent) of the variability in weight can be explained by the relationship with height?

A. [tex]$40\%$[/tex]
B. [tex][tex]$60\%$[/tex][/tex]
C. [tex]$16\%$[/tex]
D. [tex]$84\%$[/tex]

Sagot :

To determine the proportion of variability in weight that can be explained by the relationship with height, we need to use the squared value of the correlation coefficient, often denoted as [tex]\( r \)[/tex].

The given correlation coefficient [tex]\( r \)[/tex] is [tex]\( 40.40 \)[/tex]. This can be expressed as [tex]\( r = 0.4040 \)[/tex] in decimal form.

To find the proportion of variability explained by the correlation, follow these steps:

1. Square the correlation coefficient: This gives us the coefficient of determination [tex]\( r^2 \)[/tex].
[tex]\[ r^2 = (0.4040)^2 \][/tex]

2. Convert the result to a percentage: Because [tex]\( r^2 \)[/tex] represents the proportion of the variability, expressing it as a percentage involves multiplying by 100.
[tex]\[ \text{Proportion of variability explained} = r^2 \times 100 \][/tex]

Calculating this, we get:
[tex]\[ r^2 = (0.4040)^2 = 0.163216 \][/tex]
[tex]\[ \text{Proportion of variability explained} = 0.163216 \times 100 = 16.3216 \% \][/tex]

As none of the given options account for the decimal portion exactly, we round to the nearest whole number, which is 16%.

Therefore, the correct answer is:
[tex]\[ \boxed{16 \%} \][/tex]