In a fortnight of a given month, there was a rainfall of 10 cm in a river valley .If the area of the valley is 97280 km2, show that the total rainfall was approximately equivalent to the addition to the normal water of 3 rivers each of 1072 km long , 75 m wide and 3 m deep. (The answer is not given anywhere on toppers site)

There is some error in this question. The reason is given below.

 

Area of the valley, A = 97280 km²

Level in the rise of water in the valley, h = 10 cm = (10/100000) km = (1/10000) km

Thus, amount of rain fall = Ah = 97280 km² × (1/10000) km = 9.828 km³

 

Volume of water in each river = length × breadth × height = 1072 km × 75 m × 3 m = 1072 km × (75/1000) km × (3/1000) km = 0.2412 km³

 

Thus, the volume of water in three rivers = 3 × 0.2412 km³ = 0.7236 km³ ? 9.828 km³.

This shows that the amount of rain fall is not equal to the amount of water in three rivers.

 

Thus, the question has some error.