# CBSE 2017 Board Paper

Class 10 Math - Set 3 - Q15. Area, Volume

#### Video Explanation

Volume of water flowing in the canal in 40 minutes = volume of water used for irrigation.

Length of water column formed in 40 minutes = 25 × 1000 × $$frac{40}{60}$ = $\frac{50,000}{3}$ m ##### How did we get the last step? Water flows at the rate of 25 km/hr. We have convered 25 km to$25 × 1000) m.
We divided the above answer by 60 to find the length of water column formed every minute.
Finally multiplied it by 40 to find the length of water column formed in 40 minutes.

Volume of water flowing in 40 minutes = cross section area of pipe × length of water column
= 5.4 × 1.8 × $$frac{50,000}{3}$ m3 .........$1)

Volume of water used for irrigation = area of field × height of water required for irrigation
= area of field × $$frac{1}{10}$ m3 .........$2)

Equate volume of water in equations (1) and (2).
5.4 × 1.8 × $\frac{50,000}{3}$ = area of field × $\frac{1}{10}$
Area of field = 54 × 18 × $\frac{5,000}{3}$
Area of field = 324 × 5000
Area of field irrigated = 1,62,000 m2

.