In a frequency distribution, the mid-value of a class is 10 and the width of the class is 6. The lower limit of the class is

1. 6

2. 7

3. 8

4. 12

The width of each of 5 continuous classes in a frequency distribution is 5 and the lower limit of the lowest class is 10. The upper limit of the highest class is

1. 15

2. 25

3. 35

4. 40

In the class intervals 10 - 20, 20 - 30, the number 20 is included in

1. 10 - 20

2. 20 - 30

3. both the intervals

4. none of these intervals

A grouped frequency distribution table with class intervals of equal size using 250 - 270 (270 not included in this interval) as one of the class intervals is constructed for the following data :

268, 220, 368, 258, 242, 310, 272, 342, 310, 290, 300, 320, 319, 304, 402, 318, 406, 292, 354, 278, 210, 240, 330, 316, 406, 215, 258, 236.

The frequency of class 310 - 330 is

1. 4

2. 5

3. 6

4. 7