For these type of calculations, we use:

#(mol)/(volume)=M#

Now we have #170# mL #11#M #HCl# in stock. We first calculate how many mol #HCl# that is. We rewrite the above formula:

#mol=volume xx M#

Filling in the values and units gives us:

#mol=0.170 (color(red)(cancel(color(blue)(L)))) xx 11 (color(blue)((mol)/(color(red)(cancel(color(blue)(L))))))#

#mol=1.87 color(blue)(color(white)(a)mol)#

This is the amount of mol we can use to create the #0.03# M solution. We use the same formula again to calculate which volume we can create with this new concentration.

#volume=(mol)/M#

Filling in the values and units gives us:

#volume=(1.87 (color(red)(cancel(color(blue)(mol)))))/(0.03(color(red)(cancel(color(blue)(mol)))xxcolor(blue)(L^-1))#

#volume=62.3 color(blue)(color(white)(a) L)#

Therefore we can make 62.3 L of the new 0.03 #HCl# M solution.