Mathematics
The class marks of a frequency distribution are given as follows :
15, 20, 25, ………
The class corresponding to the class mark 20 is
12.5 - 17.5
17.5 - 22.5
18.5 - 21.5
19.5 - 20.5
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Answer
As the class marks are 15, 20, 25, ……… which are at equal gaps, so the classes are of equal size.
∴ size of class = difference between two consecutive class marks
= 20 - 15 = 5.
Half of class size = = 2.5
∴ Lower limit of class corresponding to the class mark 20 = class mark - half of class size
= 20 - 2.5 = 17.5
∴ Upper limit of class corresponding to the class mark 20 = class mark + half of class size
= 20 + 2.5 = 22.5
∴ Class corresponding to the class mark 20 is 17.5 - 22.5
Hence, Option 2 is the correct option.
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