At a telephone exchange, three phones ring at intervals of 20 sec, 24 sec and 30 seconds. If they ring together at 11 : 25 a.m, when will they next ring together?
Radius of cross section of a solid right circular cylindrical rod is 3.2 dm. The rod is melted and 44 equal solid cubes of side 8 cm are formed. The length of the rod is (Take Π = 22/7)