There are 7 children, you are told that youngest child is boy the probability that all of them are boys is one in?

a. 64
b. 21
c. 2
d. 128

• Since 1 child is a boy so it is a sure event.
  So the prob. of rest 6 for being a boy is (1/2)^6 ..
  =>1/64
  => ans- 64
• 11 years agoHelpfull: Yes(19) No(1)
• sorry for the above solution ..correcting now
  prob of rest are boy (1/2)^6=1/64
  
  so 64 * 1/64=1 so 64 is ans
• 11 years agoHelpfull: Yes(9) No(1)
• probability will be 1/2^6 that is 1/64 (a)
• 11 years agoHelpfull: Yes(4) No(1)
• probability cant be more than one..either the question is wrong or options are wrong..correct answer will be 1/64
• 11 years agoHelpfull: Yes(4) No(0)
• prob of rest are boy (1/2)^6=1/128
  
  so 128 * 1/128=1 so 128 is ans
• 11 years agoHelpfull: Yes(1) No(32)
• ans is 64
  probability of boy is 1/2
  there are 7 boys and we know that last one is boy
  then there are 6 childs present
  since probability of all are boy is (1/2^6)=1/64
• 6 years agoHelpfull: Yes(0) No(0)