HCU MCA 2014 Paper

The three words “MCA SCIS UH” are flashed on a digital sign board. The words individually are switched on from a switch-off position at regular intervals of 4, 7 and 9 second respectively. After they are switched on, the words are switched off after 2 sec, 3 sec and 4 sec respectively. If at time ‘t ’ all the words happened to switch off simultaneously, find the least time at which all three words will switch on simultaneously.