On a road three consecutive traffic lights change after 36, 42 and 72 seconds respectively. If the lights are first switched on at 9:00 AM sharp, at what time will they change simultaneously?
A. 9:08:04
B. 9:08:24
C. 9:08:44
D. None of these
Answer: Option B
Solution(By Examveda Team)
LCM of 36, 42 and 72, 36 = 2 × 2 × 3 × 3 42 = 2 × 3 × 7 72 = 2 × 2 × 2 × 3 × 3 LCM = 2 ×2 × 2 × 3 × 3 × 7 = 504 seconds. LCM of 36, 42 and 72 is 504 Hence, the lights will change simultaneously after 8 minutes and 24 seconds.This Question Belongs to Arithmetic Ability >> Number System
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Comments ( 7 )
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Three numbers are in ratio 1 : 2 : 3 and HCF is 12. The numbers are:
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C. 12, 24, 32
D. 5, 10, 15
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504/60 = 8.4 minutes. We need to find the exact time at which they change simultaneously, in the hour:minute:second format.
0.4 minutes = 4/10 of 60 seconds which 24 seconds. Hence, the lights will change simultaneously at 9:08:24 sharp.
Answer should be A
@Nirmala Malviya
8 Minutes = 480 Seconds (as 8*60 = 480)
So 504-480=24 Seconds
That's why ans. is 8:24
this sums ans is 8.4, how can option b is true?
if the reminder is devided with 60 then will be getting answer as 8.4 so we consider option c asthe answer .. then how option b is true