The marks scored by 50 students in a Geography examination are as follows : 60 54 40 67 53 73 37 55 62 43 44 69 39 32 45 58 48 67 39 51 46 59 40 52 61 48 23 60 59 47 65 58 74 47 40 59 68 51 50 50 71 51 26 36 38 70 46 40 51 42. (a) Using class intervals 21 - 30, 31 - 40, ..., prepare a frequency distribution table. (b) Calculate the mean mark of the distribution. (c) What percentage of the students scored more than 60%?
Explanation
(a)
Marks
frequency
mid-point
\(fx\)
21 - 30
2
25.5
51
31 - 40
10
35.5
355
41 - 50
12
45.5
546
51 - 60
15
55.5
832.5
61 - 70
8
65.5
524
71 - 80
3
75.5
226.5
\(\sum\)
50
2535
(b) Mean (x) = \(\frac{\sum fx}{\sum f}\) = \(\frac{2535}{50}\) = \(50.7\) (c) Number of students that scored above 60% : 8 + 3 = 11 %age : \(\frac{11}{50} \times 100% = 22%\)
