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CTET Feb 2014 Paper 2 Maths & Science (L - I/II: Hindi/English/Sanskrit) (Hinglish Solution)

Option 3 : 17.5

__Concept:__

- Speed: Total distance traveled by the total time taken is called speed.
- Speed measures how fast the body is moving.

\(\rm speed = \dfrac{total \ distance}{total \ time}\)

⇒ distance = speed × time

- Odometer: It is the device that is used to measure the distance traveled by a vehicle.
- Conversion of speed from km / hr to m /s

1 km = 1000 m

1 hr = 3600 second

1 km / 1 hr = 1000 m / 3600 second = \(\frac{5}{18} \ m / s\)

**Calculation:**

Odometer reading at 8:00 a.m. = 36540 km

Odometer reading at 10:00 a.m. = 36666 km.

The difference in reading of meter = 36666 km - 36540 km = 126 km

Time taken (between 10:00 a.m. and 8:00 a.m.) = 2 hrs

\(\rm speed = \dfrac{ 126 \ km}{2 \ hr} = 63 \ km /hr\)

Now, this is needed to be converted into m /s.

For this the speed has to be multiplied by 5 / 18

So, speed

\(v = 63 \times \frac{5}{18} = \frac{35}{2} = 17.5 \ m/s\)

**So, the correct option is 17.5.**