Can anyone please make me to understand example 5?
Answers
Answer:
7.5 Km
Step-by-step explanation:
Here we can Say Ajit walked 10 km by considering the number as x
he walks at 15kmph or Kilometer per hour
And he runs 20 kmph or Kilometer per hour
Before going to the calc
The formula to find time is distance/speed
thus distance by speed when he walks x km at 15 kmph is x/15kmph
which turns to x/15 as km distance is already there present in the numerator
similarly when he covers 10-x distance by running 20kmph is 10-x/20kmph
which turns to x/20 as km distance is already there present in the numerator
The time he took according to question is 37.5 min to cover 10 km
Since an hr has 60 min is 37.5/60 h
Finally x/15 + 10-x/20 = 37.5/60
so We need to do LCM of 15,20
which equals 60
thus x/15x4/4 + 10-x/20x3/3
=4x/60 + 3(10-x)/60
=4x+3(10-x)/60=37.5/60
=4x+30-3x/60 as 3(10-x) means we must multiply 3x10 and 3 x -x
=x+30/60=37.5/60 as 4x-3x= 1x or directly x
here the 60's are canceled
=x+30=37.5
=x=37.5-30
=7.5 km
Thus Ajit walked 7.5 km