A-and-B-are-walking-along-a-circular-track-They-start-from-same-point-at-8-00-am-A-can-walk-2-rounds-per-hour-and-B-can-walk-3-rounds-per-hour-How-many-times-they-cross-each-other-before-9-30-am-if-

Question Number 27399 by Rasheed.Sindhi last updated on 06/Jan/18

A and B are walking along a

circular track . They start from

same point at 8 : 00 am .

A can walk 2 rounds per hour

and B can walk 3 rounds per hour .

How many times they cross each

other before 9 : 30 am if they walk

(i) Opposite to each other .

(ii) In same direction .

?

Answered by mrW1 last updated on 06/Jan/18

v_{A} = 2 r o u n d s / h

v_{B} = 3 r o u n d s / h

(i)

2 + 3 = 5 r o u n d s / h

\Rightarrow 1 / 5 h (12 m i n u t e s) p e r r o u n d

i . e . t h e y c r o s s e a c h o t h e r e v e r y 12 m i n u t e s

f r o m 8 : 00 t i l 9 : 30 t h a t i s 90 m i n u t e s

90 / 12 = 7 . x

\Rightarrow t h e y a c r o s s e a c h o t h e r 7 t i m e s .

(i i)

3 - 2 = 1 r o u n d s / h

\Rightarrow 1 h (60 m i n u t e s) p e r r o u n d

90 / 60 = 1 . x

\Rightarrow t h e y a c r o s s e a c h o t h e r o n e t i m e .

Commented by Rasheed.Sindhi last updated on 06/Jan/18

Wonderful Sir!