Question

How long will a man take to walk round once round a circular park of radius 84 m at the rate of 4.8 km per hour?

Answer 1

Given:

Circular park radius r = 84 m.

Speed v = 4.8 km/h.

Step-wise calculation:

1. Circumference = 2πr

= 2 × π × 84

= 168π meters

2. Convert distance to kilometres:

168π m = `(168π)/1000` 

= 0.168π km

3. Time (hours) = `("Distance" (km))/("Speed" (km//h))` 

= `(0.168π)/4.8` 

= 0.035π hours

4. Numerical value:

Using π = 3.14159265:

Time = 0.035 × 3.14159265

= 0.10996 hours

Convert to minutes:

0.10996 × 60 = 6.597 minutes

= 6 minutes 35.8 seconds.

Using π = `22/7` gives 0.11 hour = 6.6 minutes = 6 minutes 36 seconds.

The man will take 0.035π hours ≈ 0.110 hours ≈ 6 minutes 36 seconds to walk once round the park.