You know its almost 2 am and i just got off from studying "Heredity and Evilotion" In BIo and i just thought to come here while having my midnight snack, then i now see your question and even tho ive done so much math in this week, i still want to answer you.....

so , as the ball are next to each other, its fig, would be like...

so here the height of cylinder (h)= 1.25x3 =3.75 inches

radius or cylinder = radius of ball = r= 1.75inches

V left in can = V of (can - 3b***s)

=Pi*r^{2}h- 3* 4*Pi*r^{3}/3

Its always to take common, makes the calculation easier...

=Pi*r^{2}(h - 3*4r/3)

=22/7 * (1.75)^{2} ( 3.75 - 12*1.75/3)

i guess you can do the rest yourself,

just a tip: while solvinf such problem which have decimal quite a lot in them , its always better to take them in fraction , it makes the calculation easier and you are less prone to errors....

hope it helps.....