6.13 Groups of children from four different classes in a school were randomly selected and sat a test, with the following test scores: Class Pupil 1234 567 A 42 63 73 55 66 48 59 B 39 47 47 61 44 50 52 C 71 65 33 49 61 D 49 51 62 48 63 54

(a) Test whether there is any difference between the classes, using the 95% confidence level for the test.

(b) How would you interpret a ‘significant’ result from such a test?