chemistry
posted by please help .
Before a trip from New York to Boston, the pressure in an automobile tire is 2.5 atm at 272 K. At the end of the trip, the pressure gauge reads 1.94 atm. What is the new Celsius temperature of the air inside the tire?
(Assume tires with constant volume.)
Answer in units of degrees C

(P1/T1) = (P2/T2)
Remember T must be in kelvin. 
i'm still not sure how to do this one. i've tried a couple of ways but it's been the wrong answer so far.

Type your work.

this is one way i did it..
2.5/272=1.94/?
.009?=1.94
?=215.6 
Set up is right.
Algebra is ok except you rounded the 2.5/272 too much. Why did you throw the other numbers away?
2.5/272 = 0.00919 (I know that's too many places in my answer but I routinely carry one more than allowed, then round at the end). My best guess is that you are off just enough that 216 is not close enough.. By the way, if the 2.5 is the problem (and not 2.50) then 2 s.f. is all you are allowed.
As an extra note, I wouldn't believe this problem at all. When you drive from New York to Boston, the temperature goes UP in a tire and not down and pressure goes UP and not down.