Question

(1) The class marks of a distribution are 94, 104, 114, 124, 134, 144 and 154. Determine the class size and the class limit of the fourth class.
​

Answer 1

Answer:

Since the class marks are equally spaced.

∴ Class size = 114 – 104 = 10

If a is a class mark and h is size of class interval, then lower limit and upper limit of the class

interval area a - h / 2 and a + h / 2 respectively.

∴ we have h = 10

∴ Lower limit of first class interval = 104 - 10 / 2 = 99

Upper limit of first class interval = 104 + 10 / 2 = 109

∴ First class interval is 99 - 109

Hence, the class intervals are 99 - 109, 109 - 119, 119 - 129, 129 - 139, 139 - 149, 149 - 159, 159 - 169.