Question

50 bells B1, B2, B3,.......B50 start ringing together. The bells ring after every 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.....50 sec respectively. Bells numbered as prime numbers ring at intervals. This interval will be the same as___

• A. sum of first 15 prime numbers
• B. HCF of 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47.
• C. LCM of first 50 numbers
• D. product of first 15 prime numbers.

Answer 1

The correct option is D

product of first 15 prime numbers.

The prime numbers falling in the interval 1 to 50 are
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47.

So the prime bells ring at intervals that will be the LCM of these prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47.

There are 15 prime numbers less than 50

The LCM of these prime numbers will be the product of the first 15 prime numbers.