do it in the grade 12 method

1. The number of bikes sold last year by various Honda dealers in a country is summarized below a) Calculate the mean and standard deviation for this sample data. Show your work. [3 marks] # of bikes Frequency 10-20 9 20-30 15 30-40 14 40-50 5 50-60 2 b) Calculate the z-score for 21 bikes sold. [1 marks]