A sign on the pumps at a gas station encourages customers to have their oil checked, and claims that 1 out of 5 cars needs to have oil added. If this is true (and assuming cars arriving independently), find the probability that at most 21 out of the next 84 cars needs oil.

Marion has a bicycle that she is planning to take for a ride. the rim of the rear wheel lies 41 cm from the center of the wheel. the tire itself has a thickness of 3 cm. in order for marion to ride her bicycle 96,712 cm approximately how many rotations will the rear wheel make?