Q3 LCM HCF

A red light flashes three times per minute and a green light flashes five times in 2 min at regular intervals. If both lights start flashing at the same time, how many times do they flash together in each hour?

(a). 30

(b). 24

(c). 20

(d). 60

We see that the red light flashes 6 times in 2 minutes

  whereas the green light flashes 5 times in 2 minutes.

  Therefore, every 2 minutes, they will flash at the same time.

  Since in an hour (or 60-minute period), there are 30 two-minute intervals,

Write Here