Answer
Before multiplying by 2: $r=0.952$
After multiplying by 2: $r=0.952$
See the demonstration below.
Work Step by Step
$r=\frac{Σx_iy_i-\frac{Σx_iΣy_i}{n}}{\sqrt {Σx_i^2-\frac{(Σx_i)^2}{n}}\sqrt {Σy_i^2-\frac{(Σy_i)^2}{n}}}$
Observe the given formula. Now, let's multiply the $x_i$ and the $y_i$, for $i = 1, 2, 3, ..., n$, by a nonzero constant $k$.
$r_{new}=\frac{Σkx_iky_i-\frac{Σkx_iΣky_i}{n}}{\sqrt {Σ(kx_i)^2-\frac{(Σkx_i)^2}{n}}\sqrt {Σ(ky_i)^2-\frac{(Σky_i)^2}{n}}}$
$r_{new}=\frac{k^2Σx_iy_i-k^2\frac{Σx_iΣy_i}{n}}{\sqrt {k^2Σx_i^2-k^2\frac{(Σx_i)^2}{n}}\sqrt {k^2Σy_i^2-k^2\frac{(Σy_i)^2}{n}}}$
$r_{new}=\frac{k^2(Σx_iy_i-\frac{Σx_iΣy_i}{n})}{k\sqrt {Σx_i^2-\frac{(Σx_i)^2}{n}}k\sqrt {Σy_i^2-\frac{(Σy_i)^2}{n}}}$
$r_{new}=\frac{k^2(Σx_iy_i-\frac{Σx_iΣy_i}{n})}{k^2\sqrt {Σx_i^2-\frac{(Σx_i)^2}{n}}\sqrt {Σy_i^2-\frac{(Σy_i)^2}{n}}}$
$r_{new}=\frac{(Σx_iy_i-\frac{Σx_iΣy_i}{n})}{\sqrt {Σx_i^2-\frac{(Σx_i)^2}{n}}\sqrt {Σy_i^2-\frac{(Σy_i)^2}{n}}}=r$
