Car A is twice as fast as car B, and car B is thrice as fast as car C. The distance covered by car C in 60 minutes will be covered by car B in:

Correct option is C

Given:
Car A is twice as fast as car B, and car B is thrice as fast as car C.
The distance covered by car C in 60 minutes
Formula Used :

$$Speed = \frac{Distance}{Time } \\ \ \\ Speed ∝ \frac{1}{Time}$$​​
Solution:
Car A is twice as fast as car B, and car B is thrice as fast as car C.
=> A = 2B
=> B = 3C
Speed ratio of A : B : C
​$$\frac{A}B = \frac{2}1 \ \ \ \& \ \ \ \frac{B}C = \frac{3}1$$​​
=> A : B : C = (2 × 3) : (1 × 3) : (1 × 1)
=> A : B : C = 6 : 3 : 1
Time is inversely proportional to the speed, Then time ratio
=> A : B : C = $$\frac{1}6 : \frac{1}3 : \frac{1}1$$​ ----(1)
Multiply by LCM 6 of the denominator (6, 3, 1) in the above equation (1)
=> A : B : C = 1 : 2 : 6
According to the question, The distance covered by car C in 60 minutes
=> 6 unit → 60 min
=> 1 unit → 10 min
Car B has taken covered the same distance in
=> 2 unit → 2 × 10
=> 20 min