7- A shaft is machined in a turning machine. Measured 10 pieces have the following dimensions 320.1, 320.5,319.9, 320.3, 319.4, 320.5, 319.5, 320.8, 319.2, 319.7 shaft length after turning operation should be 320+/-1.5 a) Draw the histogram, first calculating the interval (10p) b) Calculate standard deviation (5 p)