• 072920 77839
  • info@smartachievers.in
Menu
Back
  • JEE ADVANCE
  • JEE MAIN
  • NEET
  • BITSAT
  • CBSE BOARD
  • UP BOARD
  • CUET
JEE ADVANCE
  • CLASS XI - XII
  • CRASH COURSE
CRASH COURSE
JEE MAIN
  • CLASS XI - XII
  • CRASH COURSE
CRASH COURSE
NEET
  • CLASS XI - XII
  • CRASH COURSE
BITSAT
  • CLASS XI - XII
CBSE BOARD
  • CLASS IX
  • CLASS X
  • CLASS XI
  • CLASS XII
  • CLASS VI
  • CLASS VII
  • CLASS VIII
UP BOARD
  • CLASS IX
  • CLASS X
  • CLASS XI
  • CLASS XII
CUET
  • CRASH COURSE
Courses


Solution


Q.

Two cities X and Y are connected by a regular bus service with a bus leaving in either direction every T min. A girl is driving scooty with a speed of 60 km/h in the direction X to Y notices that a bus goes past her every 30 minutes in the direction of her motion, and every 10 minutes in the opposite direction.

Choose the correct option for the period T of the bus service and the speed (assumed constant) of the buses.                [2025]
1 10 min, 90 km/h  
2 15 min, 120 km/h  
3 9 min, 40 km/h  
4 25 min, 100 km/h  

Ans.

(2)

The relative velocity of the bus in the same direction of motion of scooty = VB-VS=VB-60

The relative velocity of the bus in the opposite direction of motion of scooty = VB+VS=VB+60

Now, distance travelled by bus in time (T) = VBT

Now, setting up equations for the distances between the buses in both cases and solve for T and VB.

VBTVB-60=30                           ...(i)

VBTVB+60=10                           ...(ii)

By solving equations (i) and (ii), we get

     T=15 min and VB=120 km/h