Aweather balloon of known initial volume is released. the air pressures ar its initial and final altitudes are known. why can't you find its new volume by using these known values and boyle's law?

You cannot find the new volume by using initial volume of the weather balloon and air pressure ai its initial and final altitudes and Boyle’s law because the given values are not the same. Boyle’s law holds for the pressure and volume of the GAS at constant temperature. Here you are given the air pressure outside the weather balloon not the inside of the balloon. They have different gases and so it would not apply.