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Question 21 - CBSE Class 10 Sample Paper for 2021 Boards - Maths Standard

Last updated at Feb. 15, 2021 by

3 bells ring at an interval of 4, 7 and 14 minutes. All three bell rang at 6 am, when the three balls will the ring together next?

3 bells ring at an interval of 4,7 and 14 minutes. All three bell rang

Question 21 - CBSE Class 10 Sample Paper for 2021 Boards - Maths Standard - Part 2

Question 21 - CBSE Class 10 Sample Paper for 2021 Boards - Maths Standard - Part 3

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Transcript

Question 21 (Introduction) 3 bells ring at an interval of 4, 7 and 14 minutes. All three bell rang at 6 am, when the three balls will the ring together next? Let the bells ring at 1, 2, 3 minutes At 6 minutes, all of them ring together. Now, this 6 is actually the LCM of 1, 2, 3 So, Time when they ring together = LCM of 1, 2, 3 Question 21 3 bells ring at an interval of 4, 7 and 14 minutes. All three bell rang at 6 am, when the three balls will the ring together next? Here, Time when they next ring together = LCM of 4, 7 and 14 Finding LCM Thus, LCM = 2 × 2 × 7 = 28 Thus, the three bells ring together after 28 minutes Hence, Time when the three bells ring together is 6:28 am

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.