The standard deviation of 100 observations is 10. If 20 is added to each observation, then what will be the new standard deviation?

The frequency distribution of the marks obtained by students in a Science examination is given below:
 

Marks	5-15	15-25	25-35	35-45
Number of students	20	30	30	20

What is the arithmetic mean?

Consider the following statements:

I. Mean and variance have the same unit of measurement.

II. Mean deviation and standard deviation have the same unit of measurement.

Which of the statements given above is/are correct?

Consider the following for the four (04) items that follow:
The frequency distribution of height of students of a class is given below:

Height (in cm	Number of Students
160-162	12
162-164	15
164-166	24
166-168	13

 

What is the total number of students whose height is less than or equal to 165 cm?