For questions 7 to 9, use the method of Worked Example 9.5 to test at the 5% significance level whether a normal distribution is an appropriate model for the given data. 7 a X [10, 20[ [20, 30[ [30, 40[ [40, 50[ [50, 60[ [60, 70[ Frequency 15 20 25 25 20 15 b X [10, 20[ [20, 30[ [30, 40[ [40, 50[ 150, 60[ [60, 70[ Frequency 150 200 250 250 200 150 reen clipping taken: 25/9/2020 10:02 am B Further X2 tests 8 a X [20, 40 [40, 60 [60, 80 [80, 100[ [100, 120[ Frequency 10 10 10 10 10 b X [ 20, 40[ [40, 60[ [60, 80[ 80, 100 100, 120 Frequency 10 20 30 20 10