Dr.Stat

Betrouwbaarheidsinterval:
$\overline{X}-\overline{Y}\pm t\times S_g\times \sqrt{\frac{1}{n}+\frac{1}{m}}$

$S_g=\sqrt{\frac{(n-1)\times S_X^2+(m-1)\times S_Y^2}{n+m-2}}$

$\overline{X}=17$, $n=6$.
$\overline{Y}=19$, $m=5$.
${\sigma }_X=1$.
${\sigma }_Y=2$.

$\overline{X}-\overline{Y}=-2$
$t=3.25$
$S_g=1.53$.
$S_g\times \sqrt{\frac{1}{n}+\frac{1}{m}}=3.01$