6. A Sign on the pumps at a gas station encourages customers to have their oil checked, and claims that one out of 4 cars needs to have oil added. If this is true and we assume cars arriving independently. (1) (5 points) Find out the probability that 7 out of the next 20 cars needs oil. [I-Iint: Write down the equation and use table 0 to find the answer.] (2) (5 points) Use normal approximation (without continuity correction) to estimate the probability that more than 12 cars out of the next 50 cars needs oil