Question

the traffic lights at three different road crossing change after every 48 sec and 72,108 sec respectively.if they change simultaneously at 7 am ,at what time will they change simultaneously again
the​

Answer 1

Step-by-step explanation:

the answer is the 24 hours

Answer 2

Answer:

432 seconds or 7 minutes and 12 seconds

Step-by-step explanation:

LCM (Lowest Common Multiple) is used to solve this problem.

We find the LCM of first two numbers and then the LCM of the answer and the third number. Hence, we get the LCM of all 3 numbers.

LCM of 48 and 72:

                6   | 48, 72

                4   |  8, 12

                        2, 3

LCM = 6 x 4 x 2 x 3 = 24 x 6 = 144

LCM of 144 and 108:

                12 | 144, 108

                 3 | 12, 9

                        4, 3

LCM = 12 x 3 x 4 x 3 = 12 x 9 x 4 = 36 x 12 = 432

Hence, the lights will change simultaneously after 432 seconds or 7 minutes and 12 seconds.