Since the moles of gas do not change, we can use a simplified version of the gas laws:
P1V1/T1 = P2V2/T2
Where the two states are noted by the subscripts 1 and 2.
We can rearrange and isolate the unknown, P2 in this case:
V2 = V1(T2/T1)(P1/P2)
Note how I've arranged the pressure and temperature variables as ratios. We can better understand, and predict the outcome of the change in conditions. The temperature does not change, so it cancels. That leaves the volume dependent on the change in pressure, by (P1/P2). We've reduced pressure by around 25%, so we should expect an increase in volume, by around that same amount.
V2 = (461ml)*(1
V2 = 607 ml
That's about a 25% increase, so I'm content.