A person covers a certain distance with certain speed if he increases his speed by 08 km/hr then he reach 10 min early . By how much time he will be late if he reduced his speed by 8 km/hr, if his initial speed is 40 km/hr .
Answer & explanation
Correct answer: option 2
Initial speed = 40 km/hr
And speed increases by 8 km/hr ,
Increased speed = ( 40 + 8 ) km/hr= 48 km/hr
Ratio initial speed : increased speed
40 : 48
speed 5 : 6
time 6 : 5
( Distance = Speed × Time , so ratio of speed and time is inverse to each other )
According to question , ( 6 - 5 )R = 10 min
Time taken with initial speed of 40 km/hr = 6 × 10 = 60 min
Now , when speed is decreased by 8 km/hr
Decreased speed = ( 40 - 8 ) = 32 km/hr
Ratio initial speed : decreased speed
40 : 32
speed 5 : 4
time 4 : 5
As , 4R = 60 min
1R = 15 min
Difference in time = ( 5 - 4 )R ⇒ 1R = 15 min