A 15 m deep well with radius 2.8 m is dug and the earth taken out from it is spread evenly to form a platform of breadth 8 cm and height 1.5 m. What will be the length of the platform?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 30.8 m.
Volume of earth is equal to the volume of the well so
r = 2.8 h = 15m
Volume of earth = π r² h = 22/7 × 2.8² × 15 = 369.6 cm³
Volume of earth = Volume of platform
so,
platform volume = length × breadth × height
369.6 = 8 × 1.5 × length
length = 369.6/12
length = 30.8 m