 Hello and welcome to the session. In this session we discussed the following question which says the average salary per head of all workers is $100. The average salary per head of 6 officers is $1200 and therefore the rest is $60. Find the total number of employees. Let us first discuss the formula for the weighted automatic average. For this we consider x1, x2, x3 and so on up to xn, b, n quantities, w1, w2, w3 and so on up to wn, b. There are respective weights. Then we have the weighted arithmetic average is equal to x1, w1 plus x2, w2 plus x3, w3 plus and so on up to xn, wn. And this means upon w1 plus w2 plus w3 plus and so on up to wn that is this is equal to summation xw upon summation w. This is the key idea that we use for this question. Let us move on to the solution now. In the question we have the average salary per head of all workers is equal to $100. Next we have the average salary per head of 6 officers is equal to $1200 and average salary per head for the rest of the employees is $60. And we are supposed to find the total number of employees. For this we suppose let the number of the rest of the employees be x. So the total number of employees would be equal to x plus since we have average salary per head of all the workers is $100. So we have the weighted arithmetic average is equal to $100. Substituting in the formula we have 100 is equal to x into 1200 since we have average salary per head of 6 officers is $1200. So 6 into 1200 average salary per head of the rest of the employees is $60 into the number of the rest of the employees which is x. The total number of employees which is 6 plus x or x plus so cross-multipline we get 100 into 6 plus x into whole is equal to 7200 plus 600 plus 100x is equal to 7200 plus x is equal to 7200 minus 600. So the total number of employees which is x plus 30x is equal to x is equal to 6600 upon 40. Now the 00 cancels 165 times is 660 therefore we have x equal to 165 is the rest of the employees. So the total number of the rest of the employees 165 the total number of employees is equal to 165 plus 6 which is equal to 170. The 171 evolved. Hope you understood the solution of the question.