Answer:
Pressure will triple (Boyle's Law)
Explanation:
Assuming a constant temperature: (compressing gases usually raises the temp significantly):
P1V1 = P2V2
P1V1 / V2 = P2
Now change V2 to 1/3 V2:
P1V1 / (1/3 V2 ) = P2 / (1/3 )
P1V1/ (1/3 v2 ) = 3 P2 <======= THE PRESSURE WILL TRIPLE
This is Boyle's Law