 Hello and welcome to the session I am Deepika here. Let's discuss a question which says in one fortnight of a given month there was a rainfall of 10 centimetre in a river valley. If the area of the valley is 97,280 kilometres square, sure that the total rainfall was approximately equivalent to the addition to the normal water of 3 rivers each 1072 kilometres long, 75 metres wide and 3 metres deep. Now first let us recall the formula for volumofic cuboid. So volumofic cuboid to breath. This is a key idea so let's start the solution. The area of the valley is 7,280 kilometres square. In one fortnight of a given month the rainfall in the valley was 10 centimetre is equal to because 1 kilometre x centimetre that is 1 centimetre is equal to 1 over 1 lakh kilometre 10 centimetre is equal to 10 upon 1 lakh kilometre. Therefore 10 fall and this is equal to 97,280 into 10 upon equal to 9728 upon 1000 kilometre cube which is equal to 9.728 kilometre cube. Therefore amount of rainfall in the valley equal to 9.920 kilometres is equal to 146 kilometre cube. Each river is given to us 1072 kilometre 10 metre which is equal to 75 upon 1000 kilometre is given to us 3 metre which is equal to 3 upon 1000 kilometre volume of water in 3 rivers into volume of water in one river which is given by the formula l into b into 1072 into 75 upon 1000 into 3 upon 1000 kilometre cube to 36 kilometre cube. All in a fortnight in the valley was 146 kilometre water of 3 rivers 0.920 plus 0.7236 with that this is equal to 146 Coincidentally equivalent to the addition to the normal water of 3 rivers.