Question: 10 minutes late to travel a certain distance at the speed of 30 km per hour If it travels at the speed of 42 km per hour and reaches ten minutes earlier then what speed should it be to travel on time

Posted by: Parmeshwar on 16.08.2022

Ans: 35 km/hr. Check attachment

time = Distance/Velocity

Right Time =  Dist/30 - 10 = Dist/42 + 10     Solving this, You will get Distance = 2100, Putting it in L.H or R.H, time will be 60

Now put these values in above equation writing as Velocity =  Distance/Time = 2100/60 = 35 Km/hour

Ideal speed is 35km/hr
Let the total distance be d km and total time be t hr. 1st case 30km/hr=d/t+1/6 d=5(6t+1) 2nd case 42km/hr=d/t-1/6 d=7(6t-1) 5(6t+1)=7(6t-1) 30t+5=42t-7 12=12t t=1hr d=5(6t+1) d=5(7) d=35km S=d/t S=35km/1hr Speed will be 35km/hr
Let travel distance be d km So(d/30) -(d/42) =20/60 This gives d=35 In the first case he took 35/30 = 1 hr 10 min That was 10 min late So In order to reach in schedule time he needs to travel 10 min faster or in 1 hr So his speed should be 35/1 or 35 kmph
In the two cases distance is same so apply the distance formula where the times are t+1/6 and t-1/6 respectively. We will get two equations by equating them we will get time by substituting this in the above equations we get distance.now we can find speed . Speed is 35 km/hr
Speed direct average speed of 30 and 42 when time is in ap then speed is in hp 2×42×30/72=35 in km/h

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