A car takes 2 hours more to cover a distance of 480 km when its speed is reduced by 8 kmph. Find its usual speed
Answer & explanation
Correct answer: option 1
Formula used here is :-
Speed = \(\frac{Distance}{Time}\)
Let us consider that usual speed = s km/h
According to question ,
\(\frac{480}{ s - 8 }\) - \(\frac{480}{ s }\) = 2
\(\frac{480s - 480s + 3840}{ s (s - 8)}\) = 2
\(\frac{ 1920}{ s (s - 8)}\) = 1
1920 = s ( s - 8 )
s² - 8s - 1920 = 0
s² + 40s - 48s - 1920 = 0
On solving it
s = 48 km/h
So, Usual speed is = s km/h = 48 km/h