$\stackrel{\text{suma kwadratoˊw zarobkoˊw w Krakowie}}{\overbrace{25\cdot \left({\left({\sigma }_1\right)}^2+6^2\right)}}+\stackrel{\text{suma kwadratoˊw zarobkoˊw w Warszawie}}{\overbrace{25\cdot \left({\left({\sigma }_2\right)}^2+5^2\right)}}=\stackrel{\text{suma kwadratoˊw zarobkoˊw w firmie}}{\overbrace{50\cdot \left(0,8^2+5,5^2\right)}}$

${\left({\sigma }_1\right)}^2+\underset{36}{\underbrace{6^2}}+{\left({\sigma }_2\right)}^2+\underset{25}{\underbrace{5^2}}=2\cdot \underset{\underset{30,89}{\underbrace{0,64+30,25}}}{\underbrace{\left(0,8^2+5,5^2\right)}}$

${\left({\sigma }_1\right)}^2+{\left({\sigma }_2\right)}^2+61=61,78$

${\left({\sigma }_1\right)}^2+{\left({\sigma }_2\right)}^2=0,78$

Jeśli ${\sigma }_1=700\text{zł}=0,7\text{tys. zł}$, to: $\underset{0,49}{\underbrace{0,7^2}}+{\left({\sigma }_2\right)}^2=0,78$ ${\left({\sigma }_2\right)}^2=0,29$ ${\sigma }_2=\sqrt{0,29}=0,538516\dots \left[\text{tys. zł}\right]$ ${\sigma }_2\approx 538,52\text{zł}$

Jeśli ${\sigma }_2=400\text{zł}=0,4\text{tys. zł}$, to: ${\left({\sigma }_1\right)}^2+\underset{0,16}{\underbrace{0,4^2}}=0,78$ ${\left({\sigma }_1\right)}^2=0,62$ ${\sigma }_1=\sqrt{0,62}=0,787400\dots \left[\text{tys. zł}\right]$ ${\sigma }_1\approx 787,40\text{zł}$