Many bike computers tell the rider the altitude they are at using a barometer and pressure differences. a biker rides on a mountain and the computer reads barometric pressures of 525 mm hg at the start and 475 mmhg at the end. assume the air density is 0.909 kg/m3 at the altitude the bike starts at. (a) (3 points) without doing any calculations, did the biker go uphill or downhill? why do you thing this? (b) (4 points) calculate how much altitude the biker gained/lost. (c) (3 points) what was the maximum altitude the biker rode at?