NCERT Solutions for Class 11 Maths Chapter 13 Exercise 13.1

Statistics has been discussed in 11th Mathematics NCERT chapter 13. Statistics is a practical subject. However, the term statistics is used in two different senses. In one sense it represents collection of data. According to A. L. Boddington, statistics is referred to as science of averages and their estimates. Statistics also means analyzing and interpreting the given data.

Almost half of 11th Mathematics chapter 13 is a mere revision of the measure of central tendency which you have already studied in class 10. Central tendency refers to the act of finding the representative value for a given data. Arithmetic mean, median and mode are the three measures of central tendency.

Calculation of arithmetic mean is the simplest. All these three can be calculated in case of individual data, discrete series and continuous series. These measures give us a rough idea about the data and question.

The topic related to dispersion is new here we study three types of deviations namely – Range, Mean deviation, standard Deviation and quartile deviation. The need to study dispersion arises because the measures of central tendency give us only a broad idea of the data.

Variability is another factor which needs to be studied. If we have to get a complete picture of the data. In exercise 13.1, we find deviation with mean and medium in various type of data.

Dispersion refers to how close or how far the variables are spread out corresponding to a particular measure of central tendency. Note that there will not be direct questions on calculation of arithmetic mean and median. However, these will be required to be calculated first.

Thus, mean deviation can be found out in two ways. From Arithmetic means and from Median. In class 11 math exercise 13.1, the basic practice is based on finding mean and medium before the deviations.