Using Python- Your research group developed two systems to measure the speed of a tennis ball. The local tennis pro suspects that the systems are not consistent with each other. To test her suspicions, she sets up both systems and records the speeds of 20 serves. The values are stored in the data file ../data/tennis.csv in the columns speed1 and speed2. The recorded speeds are in kilometers per hour. a. What is the average difference of measurements between the two systems (speed1-speed2)? b. Start the analysis by verifying the normality assumption. Perform Shapiro-Wilk test of normality on the differences (speed1-speed2). What is the p-value of the test? c. Perform the t-test (paired, 2-sided). What is the p-value? d. What is the lower limit of a 95% confidence interval on the mean difference of measurements based on the t-test? e. What is the upper limit of a 95% confidence interval on the mean difference of measurements based on the t-test? NOTE: To find an unbiased estimator of the standard deviation use np.std(speed1-speed2,ddof=1) # ddof=1 --> std = sum( (xi-xbar)^2/(n-ddfof)