Answer:
133.74 L
Explanation:
First we convert the given pressures and temperatures into atm and K, respectively:
Then we use the PV=nRT formula to calculate the number of moles of helium in the balloon, using the data of when it was on the ground:
Then, knowing the value of n, we use PV=nRT once again, this time to calculate V using the data of when the balloon was high up: