A person wants to buy 3 paise and 5 paise stamps costing exactly one rupee. If he buys which of the following number of stamps he won't able to buy 3 paise stamps.

• let 'x' be no. of 3p stamps & 'y' be no. of 5p stamps
  therefr 3x+5y=100
  he wont be able to buy 3p stamps iff he buys maximum quant of 5p stamps
  i.e. y should be max and x min
  thus lets take x=0
  3(0)+5(y)=100
  5y=100
  y=20
  thus , if he buys 20 5p stamps, he wont be able to buy 3p stamps... SIMPLE!!!
• 12 years agoHelpfull: Yes(26) No(8)
• give the options
• 13 years agoHelpfull: Yes(7) No(10)
• Ans:
  
  If You divide 1 rupees in combination of 3 and 5 paise. you will find below are the combinations occured for 3 and 5 paise respectivly.
  5,17=5*3+17*5=100
  10,14=10*3+14*5=100
  15,11=15*3+11*5=100
  20,8=20*3+8*5=100
  25,5=25*3+5*5=100
  30,2=30*3+2*5=100
  
  So if you find the combination are multiple of 6,7,8 and there is no multiple of number 9.
  
  So number 9 won't allow to buy coins exactly for this scenario.
• 8 years agoHelpfull: Yes(6) No(0)
• 3*x+5*y=100
  so if y=20
  then x will be zero .so 20
• 8 years agoHelpfull: Yes(1) No(0)
• 14
  1st calculate no of stamps taken by 5 paise
  i.e. 20.
  minus the no of stamps in multiple of 3 i.e. 6
  20-6=14
• 13 years agoHelpfull: Yes(0) No(19)