Q 1. A, B, C are running in the same direction around a circular track. The track is marked with numbers from 1 to 12, like the dial of a clock. The 12 numbers are uniformly spaced along the track. A overtakes B once at 5 and then the next time again at 9. A overtakes C once at 2 and then the next time again at 4. What is the ratio of B's speed to C's speed?

A. 7:4

B. 2:1

C. 3:2

D. 5:4

• ans 7:4
  speed of A:B = 4:16 ( from 5 to 9 B runs 4 and A (12+4) )=1:4
  speed of A:C = 2:14 ( from 2 to 4 B runs 2 and C (12+2) )=1:7
  B:C = 7:4
• 10 years agoHelpfull: Yes(26) No(8)
• A and B are meeting once at 5 and again at 9. So, by the time B has covered (5 to 9) 4 units, A has covered (5 to 5 + 5 to 9) i.e 12+4=16 units.
  Similarly, A and C are meeting once at 2 and again at 4. So, by the time C has covered (2 to 4) 2 units, A has covered (2 to 2 + 2 to 4) i.e 12+2=14 units.
  
  Thus, ratio of A:B=16:4
  i.e A/B = 16/4
  or, A=4B
  
  And, ratio of A:C=14:2
  i.e A/C=14/2
  or, 4B/C=7 (Since, A=4B)
  or, B/C=7/4
  
  Hence, ratio of B:C=7:4 (Option A)
• 8 years agoHelpfull: Yes(8) No(0)
• ans 7:4
  speed of B:A = 4:16 ( from 5 to 9 B runs 4 and A (12+4) )=1:4
  speed of C:A = 2:14 ( from 2 to 4 C runs 2 and A (12+2) )=1:7
  B:C = 7:4
• 10 years agoHelpfull: Yes(5) No(5)
• In the time B covers 4 units, A covers 16 units and in the time C covers 2 units, A covers 14 units.So ratio of speed of A:B is 16:4 and A:C to 14:2.
  So ratio of B:C is (4x14):(2x16), ie, 7:4.
• 10 years agoHelpfull: Yes(2) No(0)
• plz sumone xplain
• 10 years agoHelpfull: Yes(0) No(1)
• a must be 4 in1st case then b is n16 (12+4) so b is 4
• 10 years agoHelpfull: Yes(0) No(0)
• @ANN THERESSA
  could you explain (12+4) and (12+2) get????
• 10 years agoHelpfull: Yes(0) No(0)
• hey guys this question always wrong
  
• 9 years agoHelpfull: Yes(0) No(0)
• All started from 12. So when C covers 2 units A overtakes C at 2 not cross which means it has already covers 12 units that's why C:A = 2:(12+2). But when B covers 5 units from 12 to 5, why everyone is giving 4 units,it should be as: B:A = 5:(12+5)....or if I am wrong, then please explain the case of B...?
• 9 years agoHelpfull: Yes(0) No(0)
• https://www.doubtnut.com/related-videos/176666
• 3 years agoHelpfull: Yes(0) No(0)