The mid-values of the continuous class intervals of equal length of a distribution are 25, 34, 43, 52, 61, Then the first class interval of the distribution is :

The correct answer is (a).

The mid-values of the continuous class intervals of equal length of a distribution are 25, 34, 43, 52, 61. This means that the class intervals are 24.5 – 34.5, 34.5 – 44.5, 44.5 – 54.5, 54.5 – 64.5, and 64.5 – 74.5. The first class interval is 24.5 – 34.5.

Option (b) is incorrect because it does not include the lower limit of the first class interval. Option (c) is incorrect because it does not include the upper limit of the first class interval. Option (d) is incorrect because it is not a continuous class interval of equal length.