A-mobike-rider-moving-from-A-to-B-with-speed-20km-h-notices-that-a-bus-goes-past-it-every-21-minute-in-the-direction-of-his-motion-and-every-7-minutes-in-the-opposite-direction-Velocity-of-the-bus-is-

Facebook Tweet Pin

Question Number 47810 by Necxx last updated on 15/Nov/18

A mobike rider moving from A to B with speed 20km/h notices that a bus goes past it every 21 minute in the direction of his motion and every 7 minutes in the opposite direction.Velocity of the bus is a)25km/h b)35km/h c)30km/h d)40km/h

A m o b i k e r i d e r m o v i n g f r o m A t o B

w i t h s p e e d 20 k m / h n o t i c e s t h a t a

b u s g o e s p a s t i t e v e r y 21 m i n u t e i n

t h e d i r e c t i o n o f h i s m o t i o n a n d

e v e r y 7 m i n u t e s i n t h e o p p o s i t e

d i r e c t i o n . V e l o c i t y o f t h e b u s i s

a) 25 k m / h b) 35 k m / h c) 30 k m / h

d) 40 k m / h

Commented by Necxx last updated on 15/Nov/18

p l e a s e h e l p

Answered by mr W last updated on 15/Nov/18

x=velocity of bus in km/h (x+20)×7/60=(x−20)×21/60=distance between two buses in km (x+20)×7=(x−20)×21 x=40 ⇒answer d) distance between two buses is (40+20)×7/60=7 km 7/40×60=13⇒the bus comes every 13 minutes

x = v e l o c i t y o f b u s i n k m / h

(x + 20) \times 7 / 60 = (x - 20) \times 21 / 60 = d i s t a n c e b e t w e e n t w o b u s e s i n k m

(x + 20) \times 7 = (x - 20) \times 21

x = 40

\Rightarrow a n s w e r d)

d i s t a n c e b e t w e e n t w o b u s e s i s

(40 + 20) \times 7 / 60 = 7 k m

7 / 40 \times 60 = 13 \Rightarrow t h e b u s c o m e s e v e r y

13 m i n u t e s

Commented by Necxx last updated on 15/Nov/18

T h a n k y o u s o m u c h s i r

Facebook Tweet Pin

A-mobike-rider-moving-from-A-to-B-with-speed-20km-h-notices-that-a-bus-goes-past-it-every-21-minute-in-the-direction-of-his-motion-and-every-7-minutes-in-the-opposite-direction-Velocity-of-the-bus-is-

Leave a Reply Cancel reply