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Question 3 - Past Year MCQ (Maths Standard) - Chapter 1 Class 10 Real Numbers
Last updated at July 14, 2026 by Teachoo
Past Year MCQ (Maths Standard)
Chapter 1 Class 10 Real Numbers
Serial order wise
- Ex 1.1
- Ex 1.2
- Examples
- Case Based Questions (MCQ)
- MCQs from NCERT Exemplar
-
Past Year MCQ (Maths Standard)
- Euclid's Division Algorithm
- Decimal Expansion
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Transcript
Question 3 (Introduction) Three alarm clocks ring their alarms at regular intervals of 20 min, 25min and 30 min respectively. If they first beep together at 12 noon, at what time will they beep again for the first time ? (a) 4:00 pm (b) 4 :30 pm (c) 5:00 pm (d) 5 :30 pmLet 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 3 Three alarm clocks ring their alarms at regular intervals of 20 min, 25min and 30 min respectively. If they first beep together at 12 noon, at what time will they beep again for the first time ? (a) 4:00 pm (b) 4 :30 pm (c) 5:00 pm (d) 5 :30 pmHere, Time when they next ring together = LCM of 4, 7 and 14 Finding LCM ∴ LCM = 2 × 2 × 3 × 5 × 5 = 4 × 3 × 25 = 300 Thus, the three bells ring together after 300 minutes, i.e. after 5 hours Hence, Time when the three bells ring together is 5:00 pm So, the correct answer is (c)
