 Hello and welcome to the session. In this session we discuss the following question which says the inner circumference of a circular track is 220 meters. The track is 7 meters wide everywhere. Calculate the cost of putting up a fence along the outer circle at the rate of rupees 2 per meter. Use pi equal to 22 upon 7. Before we move on to the solution of this question let's recall the formula to find out the circumference of a circle. This is equal to 2 pi r where r is the radius of the circle. This is the key idea to be used in this question. Now let's see its solution. Consider this figure where this is the circular track which is 7 meters wide. We take let the outer radius of the circular track be capital R meters and let the inner radius of the circular track be the small r meters. So this is capital R, this is small r and this track is 7 meters wide. Now we have the inner circumference of the circular track is equal to 2 pi r meters. It's given in the question that the inner circumference of circular track is 220 meters. So we have 2 pi r would be equal to 220. So from here we get pi r is equal to 220 upon 2. Now 210 times is 220. So we get pi r is equal to 110. Now taking pi equal to 22 upon 7 we have 22 upon 7 into r is equal to 110. Further we get small r is equal to 7 into 110 upon 22. So this is equal to 7 into 5 equal to 35 meters. Now this small r is the inner radius of the circular track and this is given by 35 meters. That is we have small r is equal to 35 meters. So the inner radius of the circular track is 35 meters. Now it's given that the track is 7 meters wide. So width of the track is 7 meters and hence the outer radius of the circular track is equal to the capital R and this would be equal to small r that is inner radius of the circular track plus the width of the track that is 7 meters. Now we got small r equal to 35. So we put the value of small r here so 35 plus 7 meters is the value for capital R. So we get capital R is equal to 42 meters. That is we say outer radius of the circular track is equal to 42 meters. Now the outer circumference is equal to 2 pi into the outer radius of the circular track which is capital R. We put the value for capital R that is 42 then we put the value for pi so 2 into 22 upon 7 into 42 meters is the outer circumference. Now 7 6 times is 42 and so this comes out to be equal to 264 meters is the outer circumference. Now in the question as you can see we have to calculate the cost of putting up a fence along the outer circle at the rate of rupees 2 per meter. So we are given the rate of fencing the outer circle is equal to rupees 2 per meter. So the total cost of fencing the outer circle is given by multiplying the outer circumference which is 264 into the rate of fencing the outer circle that is 2. So 264 multiplied by 2 rupees would be the total cost of fencing the outer circle. And this is equal to rupees 528 is the total cost of fencing the outer circle. Thus rupees 528 is the final answer for this question. So we were supposed to find this. So this completes the session. Hope you have understood the solution of this question.