Question

42. A red light flashes 3 times per minutes and a green light flashes 5 times in 2 minutes at regular intervals. If both lights start flashing at the same time, how many times do they flash together in each hour?
(b) 24 (a) 30 (d) 60 (c) 20​

Answer 1

Answer:

(d) 60 is the Wright ans for the given question

Step-by-step explanation:

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Answer 2

Answer:

30 is correct answer.

Solution :-

Red light flashes 3 times per minute

=> 1 minutes = 60 second

=> 60/3 = 20 second

it means red light flashes after every

20 second

Green light flashes 5 times in 2 minutes

=> 2 minutes = 2 × 60 = 120 second

=> 120/5 = 24 second

it means green light flashes after every 24 second.

If both lights start flashing at same time

then, they flash together after

( LCM of 20 and 24 ) = 120 second or

2 minutes.

1 hour = 60 minutes

they flash together in each hours = 60/2 = 30 times

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