Question

The class marks of a frequency distribution are 7 , 13 , 19 , 25 , 31 , 37 , 43. Find the class size and all the class intervals.

Answer 1

The class marks of a frequency distribution are 7, 13, 19, 25, 31, 37, 43.

Find the class-size and all the class-intervals.

Sol. Class size = Difference between two successive class-marks = (13 – 7) = 6.

Answer 2

Given :-

➪ Class marks =  7 , 13 , 19 , 25 , 31 , 37 , 43

To find :-

➪ Class size

➪ Class Intervals

Solution :-

➪ Class size = Difference between two successive class intervals

➪ Class size = ( 13 - 7 )

➪ Class size = 6

➪ Let the lower limit of the first class interval be a

➪ Then it's upper limit will be = a + 6

➪ a + a + 6 ÷ 2 = 7

➪ 2a = 8

➪  a = ⁸⁄₂

➪  a = 4

➪ So the first class interval is 4 - 10

➪ Let the lower limit of the class interval be b

➪ Then it's upper class limit = b + 6

➪ b + b + 6 ÷ 2 = 43

➪ 2b = 80

➪ b = ⁸⁰⁄₂

➪ b = 40

➪ So the class interval is 40 - 46

Required class limits :-

➪ 4 - 10 , 10 - 16 , 16 - 22 , 22 - 28 , 28 - 34 , 34 - 40 , 40 - 46