The cross-section of a tunnel is a trapezium in shape. If the tunnel is 15 m wide at the top and 5 m wide at the bottom and the area of cross-section is 400 sq m, the depth of tunnel is?
Pick.
A) 200 m	B) 600 m	C) 400 m	D) 800 m	E) 900 m
1/2 * d (15 + 5) = 400   d = 400   ANSWER:400 m
<result>C</result>
The cross-section of a tunnel is a trapezium in shape. If the tunnel is 15 m wide at the top and 5 m wide at the bottom and the area of cross-section is 400 sq m, the depth of tunnel is?