Maths question from Naib Tehsildar exam, 2018 by JKSSB
0.2 metres is the height of water in a cylindrical container of radius ‘r’ cm. What is the height of this quantity of water if it is poured into a cylindrical container of radius ‘4r’ cm?
Last updated Jun 24, 2026
Correct Answer:
Option B —
1.25 cm
When water is poured from one container to another, its volume remains constant. We can solve this by equating the volume of the water in both cylindrical containers.
1. The Formula
The volume (V) of water in a cylinder is: V = pi r^2 h
2. Step-by-Step Calculation
Step 1: Calculate the volume in the first container Radius =( r)Height (h_1) = 0.2 { metres}V_1 = pi times r^2 times 0.2
Step 2: Express the volume in the second container
Radius = 4r Height (h_2) = ?
V_2 = pi times (4r)^2 times h_2
V_2 = pi times 16r^2 times h_2
Step 3: Equate the volumes (V_1 = V_2)
Since the quantity of water is the same: pi times r^2 times 0.2 = pi times 16r^2 times h_2
Step 4: Solve for h_2 Cancel pi and r^2 from both sides: 0.2 = 16 times h_2
h_2 = {0.2} \ {16} { metres}
h_2 = 0.0125 \text{ metres}
Step 5: Convert the unit to centimeters Since the options are in different units, let's convert metres to cm (1 { m} = 100 { cm}) h_2 = 0.0125 times 100 { cm}
h_2 = 1.25 { cm}
Final Result: The height of the water in the new container is 1.25 cm
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
