Question

Lalitha can walk at 6 m per second or cycle at 25 m per second to cover a distance of 650 M using a combination of the two Modes of transport it she takes 45 second .how long did Lalitha cycle

Answer 1

Speed she has of walking = 6 m/s
Let time taken on walking be p

Speed she has on cycle = 25 m/s
Let time taken on cycle be q

So, we have following equations
6p + 25q = 650
p + q = 45
So, p = 45 - q
Putting this in 1st equation, we get
6(45 - q) + 25q = 650
270 - 6q + 25q = 650
270 + 19q = 650
19q = 650 - 270
q = 380/19
q = 20
So, p = 25
Therefore, she cycled for 20 secs, and walked for 25 secs.

Answer 2

Lalita can walk at speed of 6m/s while on foot and 25m/s while on cycling
Let the time taken on walk be x and time taken by foot be y 
now,
Velocity = Displacement/time
Displacement= Velocity * Time

So distance covered on foot=6x
Distance covered on cycle=25y

Total distance= 6y + 25x
So,
25y+ 6x=650
We also know that total time taken was 45 sec
So,
x+y=45
y=45-x

Substituting in the above distance equation,
25y +6(45-y)=650
25y-6y= 650- 270
19y= 380
y=20
We know that,
x=45-y
x=45-20
x=25

So she walks for 25 sec and cycles for 20 sec