If the class marks in frequency distribution weights of students be 128, 137, 146, 155, 164, 173 and 182 kgs then the first class boundary is	Select the correct option.
A) 123.8	B) 123.7	C) 123.5	D) 223.5	E) 1222.2
Sol:   Rule for class boundary is = n1– (n2 – n1)/2.   So here n1 = 128, n2 = 137;   First class boundary = 128 – (137 – 128)/2 = 128 – 4.5 = 123.5   Hence option (123.5) is correct.
<result>C</result>
If the class marks in frequency distribution weights of students be 128, 137, 146, 155, 164, 173 and 182 kgs then the first class boundary is