### Aman goes to his office by car at the speed of 80 km/hr and reaches 10 minutes earlier. If he goes at the speed 30 km/hr, then he reaches 10 minutes late. What will be the speed of the car to reach on time?

a) 480/11 km/hr
b) 240/6 km/hr
c) 450/7 km/hr
d) 480/13 km/hr

Ans : a) 480/11 km/hr

SSC GD 24 Feb 2024 Paper – Mathematics

### Solution :

Let Distance = D, and Time taken = T

Distance = Speed x Time,
10 Minutes = 10/60 = 1/6 hrs

Case -1 : Aman goes to his office by car at the speed of 80 km/hr and reaches 10 minutes earlier.
D =

Case 2 : If he goes at the speed 30 km/hr, then he reaches 10 minutes late.
D =

From both cases D is same, therefore,
=
=
48T – 8 = 18T +3
->30T = 11
T = 11/30

Now find the distance from Case 1
D =
D =
D = = 16 Km

Find the required Speed
Speed = D/T =
Speed = 480/11 km/hr

### Short Trick –

When both time are equal

Use the formula for the required speed to reach on time:
Required Speed=

Substitute the values:Required Speed=

Simplify: Required Speed =

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