A certain clock marks every hour by striking a number of times equal to the hour,and the time required for a stroke is exactly equal to the time interval between strokes. At 6:00 the time lapse between the beginning of the first stroke and the end of the last stroke is 55 seconds. at 12:00 ,how many seconds elapse between the beginning of the first stroke and the end of the last stroke?
Choose the correct choice from the following choices.
A) a . 72 B) b . 115 C) c . 48 D) d . 46 E) e . 44

Rationale: "at 6 : 00 it ' ll chime 6 times . if we assume that the time taken to chime is x , then time between chimes is also x . so you have 6 chimes , which is 6 x and 5 time intervals between chimes . this means that 11 x = 55 seconds . thus x = 5 seconds . by a similar logic , at 12 : 00 , there are 12 chimes and 11 intervals so the total time is ( 12 + 11 ) x = 23 x = 115 seconds . answer b"
Answer: B