Question

A large procession of people is moving along a road of width 10m.There is a railway track
across the road. The number of people present per square meter of road is 6(on an average).
The average speed at which the procession is moving is 0.4m/s. Find number of people
crossing the railway track per second?​

Answer 1

Number of people crossing the railway track per second = 24

Explanation:

Given: A large procession of people is moving along a road of width 10m. There is a railway track across the road. The number of people present per square meter of road is 6 (on an average). The average speed at which the procession is moving is 0.4m/s.  

Find: The number of people crossing the railway track per second.

Solution: In one second, people in are of (0.4 * 10) m2 will cross the railway track.

So number of people crossing the railway track per second = 4 * 6 = 24

Answer 2

Given that,

Width = 10 m

Number of people present per square meter = 6

Average velocity = 0.4 m/s

We need to calculate the area

Using formula of area

$A=l\times d$

Put the value into the formula

$A=10\times0.4$

$A=4\ m^2$

We need to calculate the number of people crossing the railway track

Using formula for number of people

$\text{Number of people} = \text{Number of people present per square meter}\times A$

$\text{Number of people}=6\times4$

$\text{Number of people}=24$

Hence, The number of people crossing the railway track is 24.