Question

How long will a boy take to run round a square field of side 35 meters, if he runs at a rate of 9 Km/hr?
1. 52 sec
2. 50 sec
3. 56 sec
4. 54 sec

Answer 1

Correct Answer - Option 3 : 56 sec

Given:

Side of a square field = 35 meters

The speed of boy = 9 km/hr

Concept used:

To convert kilometers per hour to meters per second, multiply it with 5/18

Formula used:

Perimeter of square = 4 × side of square

Time = Distance/Time

Calculation:

We will covert its unit with m/s, so we get

9 km/hr = 9 × (5/18) = 5/2 m/s

According to the question:

Distance run around the field (d) = Perimeter of the field

Perimeter of square = 4 × side of square

⇒ d = 4 × 35m = 140 meters

Now,

Time (time taken to run around the field) = 140 m/(5/2) m/s

⇒ 140 ×(2/5) sec = 28 × 2 = 56 sec

∴ Time taken to run around the field is 56 sec.