 Hello all and welcome to the session. Today the question is, a ground plan of a house is made on the scale 1 centimeter to 20 meters. Find scale factor of the plan, find the length and width on the plan of the room 35 meters by 20 meters. What area on the ground is represented by 1 centimeter square on the plane? Now before starting the solution of this question, we should do some results. And that are the model or map of a plane figure is drawn to the scale 1 is to p then factor k will be equal to 1 over p. And length of the model or map will be equal to k times length of the actual figure. These two results will work as a key idea for solving out this question. And now we will start with the solution. Given scale is equal to 1 centimeter is to 20 meters. Now converting both of them in same units. It will be equal to 1 centimeter is to 20 meters will be converted into centimeter and it will become 2000 centimeters. Therefore scale will be equal to 1 is to 2000. This implies factor k is equal to 1 over 2000. Now we have to find out length of the room on the plane. And in the question length of the room is given as 25 meters. Length of the room is equal to 25 meters. Converting into centimeters it will be 25 into 100 centimeters. This will be equal to 2500 centimeters. Now here the key idea of formula is given which is length of the model or map is equal to k times length of the actual figure. Now using this formula length of the room on the plane is equal to k times true length of the room. Which is equal to the value of k is 1 over 2000 into actual length of the room is equal to 2500 centimeters. Further these zeros will be cancelled with the zeros here. 5 into 4 is 20 and 5 into 5 is 25. So it will be equal to 5 by 4 centimeters which will give 1.25 centimeters. Therefore length of the room on the plane is equal to 1.25 centimeters. And now we have to find the breadth of the room on the plane. Here the breadth of the room is given as 20 meters. Now breadth of the room is equal to 20 meters which is equal to 20 into 100 centimeters which will give 2000 centimeters. Now according to the formula which is given with the key idea breadth of the room on the plane is equal to k times true breadth of the room. Now putting the values of k and actual breadth of the room k is 1 over 2000 into breadth of the room is 2000 centimeters. This will be cancelled with this and it will give until as 1 centimeter. Therefore breadth of the room is equal to 1 centimeter. Now given k is equal to 1 centimeter is to 20 meters. Now here 1 centimeter represents 20 meters. This implies 1 centimeter square will represent 20 meters square which is equal to 400 meters square. Thus 400 meters square area on the ground is represented by 1 centimeter square on the plane. Thus we have got the solution as same factor k is equal to 1 over 2000. Secondly breadth of the room is equal to 1.25 centimeters. Thirdly breadth of the room on the plane is equal to 1 centimeter. Fourthly the area of 200 meters square on the ground is represented by 1 centimeter square on the plane. So this is the solution of this question and that's all for this session. Hope you all have enjoyed this session.