n a study to analyse performance in a 2012 examination series the following scores in a

percentage were compiled for a sample of 100 candidates.

42,51,52,53,61,62,63,64,71,72,81,46,53,54,55,63,64,65,66,73,74,82,48,57,58,59,67,68,69,77,78,

87,43,54,56,64,65,66,67,74,75,84,47,52,53,54,62,63,64,65,72,73,82,45,56,57,58,66,67,68,69,76,

77,86,44,55,56,57,65,66,67,75,76,85,49,50,51,52,60,61,62,70,71,51,52,53,61,62,63,71,72,58,59,

57,68,69,67,78,79,80

a) Arrange the data in equal classes of size 10 starting from 40 percent.

b) Using an ogive for the data, find

i) The approximate percentage of the candidates who passed the examination if the pass

mark was 62.5 percent.

ii) The pass marks if 90 percent of the candidate passed examination.

c) Verify whether it would be appropriate to use the properties of normal probability

distribution in analysing the data