 Hi, and welcome to the session. This is Kaisa Pauli in question. The question says, find the mean deviation about the mean for the data in exercises nine and 10. This is the data given to us, and we have to find the mean deviation about the mean of this data. We will first learn the steps which are involved in the calculation of mean deviation about mean of a continuous frequency distribution. In the first step, we obtain the midpoint of each class interval, which is denoted by xi, and this xi is equal to upper limit plus lower limit divided by two. Then we find the mean of the given data by using the formula mean is equal to one by n into summation i goes from one to n, fi, xi, where n is equal to summation i goes from one to eight and five. In the second step, we find the deviation of e to xi from x bar, that is x one minus x bar, x to minus x bar, so on, x in minus x bar. In the third step, we find the absolute value of each deviation, that is, what the minus sign, if it is there, that is mod of x one minus x bar, mod of x two minus x bar, and so on. And in the last step, we find the mean of the absolute values of the deviations. This mean is the mean deviation about mean, that is, mean deviation about mean is equal to one by n into summation i goes from one to n, fi into mod xi minus x bar, where n is equal to summation i goes from one to n, fi. Always remember these steps. So, giving this in mind, let's now begin with the solution. We will first make a table from the given data. We have written the given information in the first two columns. We will first find midpoint of each class interval. We know that midpoint is obtained by adding the upper and lower limit, and then dividing the sum of upper and lower limit by two. Now, the first class interval is 95 to 105, where the lower limit is 95 and upper limit is 105, so midpoint is 95 plus 105 divided by two, and this is equal to 200 by two, and 200 by two is 100. Then we have 105 plus 150 by two, and this is equal to 110. Then we have 115 plus 125 by two, this is equal to 120. Then we have 125 plus 135 by two, this is equal to 130. 135 plus 145 by two is 140, and 145 plus 155 by two is 150. Now we will find product of fi and xi. In the first row, fi is nine and xi is 100, so fi into xi is 900, then we have 30 into 110 is equal to 1,430, 26 into 120 is 3,120, 30 into 150 is 3912 into 140 is 1,680, then into 150 is 1500. We know that n is equal to summation i goes from one to n fi. Here, n is equal to summation i goes from one to six fi, and this is equal to nine plus 13 plus 26 plus 30 plus 12, plus 10, this is equal to 100. So some of all these frequencies is 100. Now we will find summation i goes from one to six fi xi, this is equal to 900 plus 1430 plus 3120 plus 3900, plus 1680 plus 1500, and this is equal to 12,530. We know that mean is equal to one by n into summation i goes from one to six fi xi, and this is equal to one by 100 into 12,530, and this is equal to one to 5.3. So mean of the given data is one to 5.3, xi minus x bar, and the first row xi is 100, and we know that x bar is equal to one to 5.3. So we have 100 minus one to 5.3, and this is equal to minus 25.3. Then we have 110 minus one to 5.3, and this is equal to minus 15.3, then we have minus 5.3, then we have 4.7, 140 minus one to 5.3 is 14.7, 115 minus one to 5.3 is 24.7. Now we will find mod of xi minus x bar. Absolute value of minus 25.3 is 25.3, absolute value of minus 15.3 is 15.3, and absolute value of minus 5.3 is 5.3, absolute value of 4.7, 14.7, and 24.7 is 4.7, 14.7, and 24.7. We will find product of fi and mod xi minus x bar. 9 into 25.3 is 227.7, 13 into 15.3 is 198.9, 26 into 5.3 is 137.8, 13 into 4.7 is 141, 12 into 20.7 is 176.4, 10 into 24.7 is 247. On adding all this, we get 1128.7. I goes from 126 fi into mod xi minus x bar is 1128.7. Now we will find mean deviation about me. Now mean deviation about me is equal to 1 by n into summation. I goes from 1 to 6 fi into mod xi minus x bar. This is equal to 1 by 100 into 1128.7, and this is equal to 11.28. Hence our required answer is 11.28. So this completes the session. Hi, and take care.