Question

1. A watch. At the hour. The bell rings twice, the bell rings 2 times at 2 o'clock, •••, the bell rings 12 times at 12 o'clock. How many times will Mate ring the bell in 24 hours? . A 78 B) 136 C) 156 D 196​

Answer 1

Total bell rings in 12 hours = 1+2+...+12

Total bell rings in 24 hours = 2(1+2+...+12) {because, after 12 o'clock, the clock resets and starts from 1 instead of 13}

Total bell rings = 2(78)

= 156