The cross-section of a cannel is a trapezium in shape. If the cannel is 12 m wide at the top and 2 m wide at the bottom and the area of cross-section is 4200 sq m, the depth of cannel is?	Select the correct option.
A) 500	B) 600	C) 700	D) 800	E) 900
1/2 * d (12 + 2)   = 4200   d = 600   Answer: 600
<result>B</result>
The cross-section of a cannel is a trapezium in shape. If the cannel is 12 m wide at the top and 2 m wide at the bottom and the area of cross-section is 4200 sq m, the depth of cannel is?