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

Thus, amount of rain fall in 14 day = Ah = 97280 km2 × (1/10000) km = 9.828 km3

Amount of rain fall in 1 day = 9.828 /14 = 0.702km3

Volume of water in 3 rivers = length × breadth × height = 1072 km × 75 m × 3 m = 1072 km × (75/1000) km × (3/1000) km = 0.2412 km3 x3 = 0.7236 km3

This shows that the amount of rain fall is approximately equal to the amount of water in three rivers.

__Optional Exercise – 13.5 - 10th Mathematics –Surface area and Volume__