1.Number of combination of 11 coins tossed at a time where 9th and 10th coin is always head?
2.xy is number difference between y^3+x and x^3+y is always divisible by n,what is max n here?

• number of combination will be (2^9)*2.
  here heads are fixed in 9th and 10th position. so they vl make 2 combination and TTTTTTTTT... vl make 2^9 combination and ..
  so the ans is (2^9)*2.
• 10 years agoHelpfull: Yes(4) No(1)
• 2^(11-2)=2^9 is the right ans because 9th and 10th tossed are fixed
  so total no of events will be 2^(11-2)=2^9
• 10 years agoHelpfull: Yes(3) No(1)
• 1.number of combinations of 11 coins tossed where the 9th and 10th is always head
  probability of a coin is 1/2(h/t)
  the combination is 9tails and 2heads T T T T T T T T T H H
  therefore (1/2^11)x(11!/9! 2!)
  =55/(2^11)
  
• 10 years agoHelpfull: Yes(0) No(3)