If the base radius of 2 cylinders are in the ratio 3 : 4 and their heights are in the ratio 4 : 9, then the ratio of their volumes is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 1 : 4
Given :
Base radius ratio = r1 : r2 = 3 : 4
Height ratio = h1 : h2 = 4 : 9
Formula used :
Volume of cylinder = ------ (1)
Calculations :
Using equation (1), we get
Let the radius of the cylinders be r1 and r2 and height be h1 and h2
According to the question, we have
⇒ Volume(V1) of first cylinder : Volume(V2) of second cylinder
⇒ V1 : V2 = :
⇒ V1 : V2 = (3)2 × 4 : (4)2 × 9
⇒ V1 : V2 = 9 × 4 : 16 × 9
⇒ V1 : V2 = 36 : 144
⇒ V1 : V2 = 1 : 4
Short trick :
| Understanding | Application |
| Tricks | The volume of the 1st cylinder/Volume of the 2nd cylinder =
πr12h1/πr22h2 = [3 × 3 × 4]/[4 × 4 × 9] = 1/4 |
| Hence | 1 : 4 |