This question is taken from real numbers chapter in which we have given that traffic lights at three different road crossing change after every 48 seconds, 72 seconds and 108 seconds respectively and we have to find at what time will they change simultaneously if they they change simultaneously at 7 : 00 a.m.
Kindly solve the above problem in detail
RS Aggarwal, Class 10, chapter 1B, question no 26
Consider the problem
The traffic light at three different road crossing change after every 48seconds,72seconds and 108seconds respectively
So,
48=2×2×2×2×3
72=2×2×2×3×3
108=2×2×3×3×3
Therefore, L.CM of 48,72,108 is
(2×2×2×2×3×3×3)=432
So, time when they change again =432seconds
But we need to find time after 7am So, first we convert 432seconds into minutes.
Time=432second=432/60minutes∴Time=7 minutes 12 seconds
Thus,
Required time =7am+7minutes 12seconds
=7:07:12am