For a plot of land of 100 m × 80 m, the length to be raised by spreading the earth from stack of a rectangular base 10 m × 8 m and vertical section being a trapezium of height 2 m. The top of the stack is 8 m × 5 m. How many centimeters can the level raised?
Answer : Option D
Explanation :
The stack is in the form having vertical cross section of trapezium.
∴ Volume of Earth in the stack = Area of cross section
of trapezium × Height
∴ Volume = $1\over2$(10+5) x 2 x 8 = 15 x 8 $m^2$ According to the question,
Volume of Earth to be spread = (Area of field) × Level raised
∴ Level raised =$15X8\over100X80$ = $15\over1000$ m= 1.5cm
