The manufacturer of a sports car claims that the fuel injection system lasts 48 months before it needs to be replaced. A consumer group tests this claim by surveying a random sample of 10 owners who had the fuel injection system replaced. The ages of the cars at the time of replacement were (in months): 21 48 49 48 53 46 30 51 42 52 (i) Use your calculator to calculate the mean age of a car when the fuel injection system fails x and standard devia