Question

Traffic light at one particular crossing change after every 40 seconds. The traffic light at the next crossing changes after every 32 seconds. At a certain time they change together. After what time they will change together?
1. 2 min 40 sec
2. 1 min 20 sec
3. 3 min 20 sec
4. 2 min 20 sec

Answer 1

Correct Answer - Option 1 : 2 min 40 sec

The traffic light at one particular crossing change every 40 seconds.

The traffic light at the next crossing changes every 32 seconds.

The time required to change together is equal to the least common multiplier of both times.

Required time = LCM (40, 32) = 160 sec = 2 min. 40 sec.