electric running buzzer rang after every 60 sec.and second buzzer rang after every 62 sec.both rung together at 10'o clock.after that at what time both rang together?  Options:
A) morning 10:30	B) morning 10:31	C) morning 10:59	D) morning 11:00	E) none of these
difference of time between together ringing of buzzer=l.c.m of 60 sec. and 62 sec.   (2*30*31) sec.={2*30*31}/60=31 minute   hence,next time they rang together at morning 10:31   answer morning 10:312*30*31 /60= 
<gadget id="calculator">2*30*31 /60</gadget>
<output>31</output>
31 minute   hence,next time they rang together at morning 10:31   answer morning 10:31
<result>B</result>
electric running buzzer rang after every 60 sec.and second buzzer rang after every 62 sec.both rung together at 10'o clock.after that at what time both rang together?