Question

By running 900 meter and walking another 900 metres, a man covers a distance of 1800 m in 21/2 minutes. If he had run 20% slower and walked 20%faster, he would have taken just 10minutes to cover the distance. Find the time talking by him to run 100 m

Answer 1

Step-by-step explanation:

Time =km / hr (or) m/ sec

Time =1800m / 21/2 mins

Time =1800 / 21 mints can be written as 21 × 60 secs

Time=1800 / 1260 ÷2

Time =1800 /630.

Time=2.857

Hope it will help you

Answer 2

Answer:

Step-by-step explanation:

easy my friend

find average speed

formula=2v1v2/v1+v2

speed when running=x-v1

speed when walking=y=v2

average speed=2xy/x+y

t=dis/speed

10.5=1800(x+y)/2xy

10.5xy=900x+900y

now v1 is decreased and v2 is incresed by 20%

v1=0.8x

v2=1.2x

average speed=1.92xy/0.8x+1.2y----1

same find time-d/s

10=1800(0.8x+1.2 y)/1.92xy

u get x=540y/216

substitute in 1

u get y=120 and x=300

time=dis/speed=100/300=1/3