9. The traffic lights at three different road crossing change after every 48 sec; 72 sec; and 108 sec., respectively. If they all change simultaneously at 8:20:00 hrs, then they will again change simultaneously at
a. 8:27:12 Hrs
b. 8:27:24 Hrs
c. 8:27:36 Hrs
d. 8:27:48 Hrs

• take lcm of three 48,72,108
  
  432 sec
  
  
  convert it into the Time format
  
  a) 8:27:12 hrs
• 8 years agoHelpfull: Yes(14) No(0)
• take lcm of the given time....lcm denote the time on which they change simultaneously...so lcm is 432=7min 12 second..so after 7min 7 sec they change simlt.....ans is 8:27:12
• 8 years agoHelpfull: Yes(2) No(0)
• take lcm of 48,72,108
  lcm=432
  432/60=7.2
  add 7min2sec to8:20:00
  ans would be
  8:27:20
• 8 years agoHelpfull: Yes(1) No(5)
• take the lcm of all numbers lcm(48,72,108)=432
  432s time taken by all signals, convert into hour=(432/60)= 7 hour 12sec
  they all change simultaneously at 8:27:12 hrs
  
  ans:a
  
• 8 years agoHelpfull: Yes(0) No(0)
• Take lcm of all the three no which is 432 second now add it to the given time thus we get 8:27:12
• 8 years agoHelpfull: Yes(0) No(0)
• Take lcm of 48,72,108 then divide it by 60 as we are given options in form of hour,min and second so as per question we are given 8 hr 27 min for second lcm /60= 12
• 8 years agoHelpfull: Yes(0) No(0)
• Ans. a -8:27:12 Hrs
  LCM of 48,72,108 - 432 sec.
  420 sec+12 sec - 7 min+12 sec
  So, 8:27:12 Hrs.
• 8 years agoHelpfull: Yes(0) No(0)
• l.c.m. of 48,72,108 = 432.
  light will again change simultaneously after every 432 sec i.e. 7 min, 12sec.
  Hence next = 8:27:12 hrs.
• 7 years agoHelpfull: Yes(0) No(0)