Write the class mark of the class 130-150.

If the median of the data arranged in ascending order 8, 9, 12, 18, x+2, x+4, 30, 31, 34, 39 is 24. Then, find the value of x.

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

Let l be the lower-class limit of a class-interval in a frequency distribution and m be the mid-point of the class. Then, find the upper-class limit f.

In a group of 10 students, marks obtained in a subject are as follows: 23, 22, 45, 38, 49, 23, 45, 10, 45, 39. Find the following:
(i) Mean marks of class
(ii) Median marks of class
(iii) Modal marks of class