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7. The average number of kilometers a person drives per day is 40 km. A researcher wishes to see if people below age of 60 drive more than 40 km a day. She selects a random sample of 35 drivers below the age of 60 and finds that the mean number of kilometers driven is 42.7 km. The population standard deviation is 4.5 kilometers. At 0.05 level of significance, is there sufficient evidence that those drivers below 60 years old drive more than 40 km per day on average? Assume that the variable is normally distributed. Express your answers correct to 2 decimal places. Enter the answers in this order: a) to d) [6 marks] a) What test should be performed (z or t)? b) Find the critical value(s). c) Calculate the test statistic