Four bells ring simultaneously at a certain instant.  Thereafter, they ring at intervals of 6, 8, 10, 12 and 24 seconds respectively. In how many minutes will they ring together again for the first time?

18 min

LCM of (6, 8, 10, 12, and 24) = 1080 seconds = 18 min

Hence, 

The bells will ring again together for the first time after 18 min