A and B start running on a circular track of length 1200 meters with

Question

A and B start running on a circular track of length 1200 meters with speeds in the ratio of 1 : 5 and A running clockwise and B anticlockwise. At what distance from the starting point, measured clockwise, would the point of their 4th meeting be?

A. 200 mts
B. 400 mts
C. 600 mts
D. 800 mts
E. 1000 mts

A. 200 mts 
B. 400 mts 
C. 600 mts 
D. 800 mts 
E. 1000 mts

PTD1995 · Accepted Answer

Option D

We can say that for every 100m that A runs, then B runs 500m. Logically, if A runs 200m, then B runs 1000m, meeting for the first time. Thus, for every 200m that A runs, they will meet.
So, the second time they meet A will have run 400m, the third time 600m and the fourth 800m.

jfranciscocuencag · Answer

PTD1995

Hello!

If its circular, why not 400mts?

I mean its 800 mts from the star point anticlockwise but, what about the distance from clockwise?

Kind regards!

fireagablast · Answer

Why is the answer D? You can also just visualize this just like a clock.
Runner B goes reverse 1, while runner A goes forward (clockwise) by 5. Numbers reset at 12 (i.e 13=1, 14=2, etc)

Runner B:Runner A
12:12 or 0:0
11:5
10:10 - meeting 1
9:3
8:8 - meeting 2
7:1
6:6 - meeting 3
5:11
4:4 - meeting 4

Runner A meets at 400m clockwise, while Runner B meets 1200-400 = 800m counterclockwise.

Edit: NVM - i had the runners speeds reversed. Answer is 800m

ScottTargetTestPrep · Answer

We can re-express the ratio of A : B as 2 : 10. Thus, for every 200 m run by A, we see that B will have run 1,000 m. The first time they meet, A has run 200 m clockwise, and B meets A at that point, having run 1,000 m. Their second meeting occurs when A has run another 200 m (for a total of 400 m). The third meeting occurs when A has run an additional 200 m, for a total of 600 m, and finally, the fourth meeting occurs when A has run a total of 800 m clockwise.

Answer: D

Kinshook · Answer

Given: A and B start running on a circular track of length 1200 meters with speeds in the ratio of 1 : 5 and A running clockwise and B anticlockwise.

Asked: At what distance from the starting point, measured clockwise, would the point of their 4th meeting be?

Let speeds of A & B be x and 5x respectively

A moves = x/6x * 360 = 60 degrees for each meeting clockwise
For 4th meeting, A moves = 60 *4 = 240 degrees clockwise

Distance covered = (240/360)*1200 = 800 m

IMO D

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