<u>Answer:</u> The new volume of the balloon will be 583.5 L
<u>Explanation:</u>
To calculate the volume when temperature and pressure has changed, we use the equation given by combined gas law.
The equation follows:

where,
 are the initial pressure, volume and temperature of the gas
 are the initial pressure, volume and temperature of the gas
 are the final pressure, volume and temperature of the gas
 are the final pressure, volume and temperature of the gas
We are given:
![P_1=1.15atm\\V_1=3.60L\\T_1=20^oC=[20+273]K=293K\\P_2=5.40\times 10^{-3}atm=0.00540atm\\V_2=?\\T_2=-50^oC=[-50+273]K=223K](https://tex.z-dn.net/?f=P_1%3D1.15atm%5C%5CV_1%3D3.60L%5C%5CT_1%3D20%5EoC%3D%5B20%2B273%5DK%3D293K%5C%5CP_2%3D5.40%5Ctimes%2010%5E%7B-3%7Datm%3D0.00540atm%5C%5CV_2%3D%3F%5C%5CT_2%3D-50%5EoC%3D%5B-50%2B273%5DK%3D223K)
Putting values in above equation, we get:

Hence, the new volume of the balloon will be 583.5 L