Question

We have four concentric circles, each circle made of blinking lights. The outermost circle lights blink every 3 sec, the next circle lights blink every 5 sec, the next one every 6 sec and the innermost one every 8 sec. At 12 oclock, lights of all the four circles blink together. By 1 oclock, how often would they have blinked together?

Answer 1

Answer:

30 times

Step-by-step explanation:

the interval at which they blink together is LCM (3,5,6,8).

so every 120s or 2 min they'll blink together.

so they would've blinked 30 times together in the period of 1 hour

Answer 2

Answer:

The correct answer is 30

Step-by-step explanation:

Given data  

There are four concentric circles with blinking lights

The outermost circle light blink every 3 sec

The next circle light blinks every 5 sec

The next circle light blinks every 6 sec

The innermost light blinks every 8 sec

⇒ lights of all the four circles blink together at 12'o clock  

⇒ here we need to find By 1'o clock how often would they will blink  together

now find the LCM (3, 5, 6, 8)  

3 = 3 × 1

5 = 5 × 1

6 = 2 × 3 × 1  

8 = 2 × 2 × 2  

⇒ 2 × 2 × 2 × 3 × 5 = 120 sec = 2 minutes  

⇒ for every 2 minutes all lights blink together

⇒ given that at 12'o clock all lights of 4 circles blinks together  

⇒ after 12 for every 2 minutes all lights will blink together

⇒ by 1'o clock all lights blink together for 30 times