The three words "TATA Assets Rock" are flashed such that the words individually are switched on at regular intervals of 4,7 and 9 seconds respectively and after they are switched on, the words are switched off after 2 sec, 4 sec and 5 sec respectively. If at time 't' all the words happened to switch off simultaneously, find the least time 't' which all three words will switch on simultaneously.

• If we make time line for a(=tata), b(=assets) & c(=rock), we find dat a will on at (4, 10, 16, 22,...) giving equation_1 4x + 2(x-1). For b, we find dat it will on at (7, 18, 29,...) giving equation_2 7y+4(y-1) & c will be on at (9, 23, 27,...) giving equation_3 9z+5(z-1). Now, we have to find those integer values of x, y & z for which value of above 3 equations is same. By equating options with these 3 equations, only option, 94 is providing values close to integer for x, y & z.
• 8 years agoHelpfull: Yes(1) No(0)
• The first word will switch on after 4x+(4−2) seconds from t
  
  The second word will switch on after 7y+(7−4)
  seconds from t
  
  The third word will switch on after 9z+(9−5)
  seconds from t.
  ⇒ If at t′, all the switches on together
  t′−t=4x+2=7y+5=9z+4
  
  We want the least value of t′−t
  for which x,y and z
  
  are integers.
  
  Check the options we get 94 the least option.
  
  
  
• 8 years agoHelpfull: Yes(0) No(1)