Question

At 3:40 PM a thief robbed a bank and ran at a speed of 30km/hr. At 4:00 PM the police were informed about the robbery and they started chasing the thief. At what time they will catch the thief if the speed of police is 150% of a thief?

1.

4:20PM

2.

4:30PM

3.

4:40PM

4.

5:20PM

5. 5:10PM

Answer 1

Correct Answer - Option 3 :

4:40PM

Given:

Speed of a Thief = 30km/hr.

 At 3:40 PM a thief robbed a bank.

Formula Used:

Speed = Distance/ Time

Relative Speed (While Chasing):

⇒Total Distance covered / Total time taken

Calculation:

Speed of Police:

⇒ 150% of a Thief = 150/100 × 30 = 3/2 × 30 =45km/hr.

In 20 minutes thief will cover,

⇒ 30 × 20/60 → 10km.

Relative speed ⇒  (Police-Thief) = Distance covered by thief / total time taken

∴ 45 – 30 = 10/Time taken

∴ 15 = 10/Time taken

∴ Time taken = 10/15 = 2/3 hours.

∴ hours. = 2/3× 60 = 40 minutes

∴ Police will take 40 minutes to catch the thief.

∴ Police will catch a thief at 4:40 PM