Question

a thief after commiting a theft runs at a uniform speed of 50 m/minutes. after 2 minutes, a policeman runs to catch him. he goes 60m/minute in first minute and increases his speed by 5m/minute every suceeding minute. after how many minutes the police man will catch the thief

Answer 1

Answer:

5 minutes

Step-by-step explanation:

Speed of the theif is 50 m/min

In 2 mins, the theif covers 100 m.

After 2 mins, the policeman runs to catch him, so in the third minute the policeman covers 60 m.

In the third minute the thief would cover 150 m.

 

Now policeman increases his speed by 5 m/ min (Student be careful units for speed is 5 m/min NOT just metres)

So, in the fourth minute:

Distance covered by policeman = 60 + 65 = 125 m

Distance covered by thief = 200 m

 

In the fifth minute:

Distance covered by policeman = 125 + 70 = 195 m

Distance covered by thief = 250 m

 

In the sixth minute:

Distance covered by policeman = 195 + 75 = 270 m

Distance covered by thief = 300 m

 

In the 7th  minute:

Distance covered by policeman = 270 + 80 = 350

Distance covered by thief = 350 m

Hence, after 7 minutes the policeman will catch the thief.

But 7 minutes of thief is 5th minute of policeman