Respuesta :
First of all we have to re write the equation like this:
[tex]W(t)=\left \{ {{33-\frac{(10.45+10\sqrt{v}-v(33-t) }{2204}if 0\leq v<1.79} \atop {33-1.5958(33-t)if 1.79\leq v<20 }} \right.[/tex]
To solve this problem we have to replace the values ([tex]t=15[/tex] and [tex]v=12[/tex]) in the previous equation, as we can see in the limits of the equation the value given for v would fit in the second condition ([tex]1.79\leq 12<20[/tex]) so we would use the second part of the equation like this:
[tex]W(t)=33-1.5958(33-t)\\W(15)=33-1.5958(33-(15))=33-1.59589(18)=33-28.7244=4.2756[/tex]
and rounding to one decimal place (we round up because the next digit from the first decimal place is bigger than 5) :
[tex]W(15)=4.3[/tex]