1.4-1. A plane drops from the altitude 5500 m to 2700 m. If the uncertainty of the altimeter is 40 m, how much altitude was lost (with uncertainty?) [2800±80m]

1.4-2. A cube with the side 85±7 cm has the mass 420±30 kg. What is its density, with uncertainty? [684±218 kgm^-3 or approx. 700±200 kgm^-3 ]