Planet fourfi resides in 4-dimensional space and thus the currency used by its residents are 3-dimensional objects. The rupee notes are cubical in shape while their coins are spherical. However the coin minting machinery lays out some stipulations on the size of the coins.
• The diameter of the coins should be at least 64mm and not exceed 512mm.
• Given a coin, the diameter of the next larger coin is at least 50% greater.
• The diameter of the coin must always be an integer.
You are asked to design a set of coins of different diameters with these requirements and your goal is to design as many coins as possible. How many coins can you design?
•a)8
•b)6
•c)9
•d)5

• min radius=64mm
  next we have=64+50%of 64=64+32=96
  next we have=96+50%96= 96+48=144
  =144+50%of144 =144+72=216
  =216+50%of216 = 216+108=324
  =324+50%of324 = 324+162=486
  =486+50%of486= 486 + 243 =729>512
  so we have 64mm,96,144,216,324,486
  that is 6 coins
  
  option (b) is correct
• 13 years agoHelpfull: Yes(27) No(0)
• 64mm.........1st coin
  64+32=96.....2nd coin
  96+48=144....3rd coin
  144+72=216...4th coin
  216+108=324..5th coin
  324+162=486..6th coin
  486+50%of 486 exceeds 512
  so 6 coins can be designed
• 13 years agoHelpfull: Yes(3) No(0)
• ans is 6
  64*(1.5)pow x < 512 where x is the number of coins
  therefore x
• 13 years agoHelpfull: Yes(1) No(0)