A drawer holds 4 red hats and 4 blue hats. What is the probability of getting exactly three red hats or exactly three blue hats when taking out 4 hats randomly out of the drawer and immediately returning every
hat to the drawer before taking out the next?
option
A. 1/2
B. 1/8
C. 1/4
D. 3/8

• 4 red, 4 blue(asked exactly 3r or 3b)
  probability for drawing red hat is 4/8:he return every hat to drawer
  firstly exactly 3 red is 4/8*4/8*4/8*4/8=1/16
  exactly 3 blue is 4/8*4/8*4/8*4/8=1/16
  1/16+1/16=1/8
  
• 11 years agoHelpfull: Yes(14) No(3)
• first here 4 red hats are identical and 4 blue hats are identical
  consider drawing 3 blue hats and 1 red hat
  drawing red hat first and 3 blue hats second third and fourth
  probability of drawing red hat is 1/2 since (4red/8total)
  probability of drawing red hat first is =(1/2)*(1/2)*(1/2)*(1/2)
  similarly drawing red second =(1/2)*(1/2)*(1/2)*(1/2)
  ..
  probability of drawing 1 red hat=drawing red first+..drawing red fourth
  =4*(1/2)^4
  similarly drawing 1 blue hat=4*(1/2)^4
  so final probability=4*(1/2)^4+4*(1/2)^4
  =2*4*(1/2)^4
  =1/2
  
  
• 11 years agoHelpfull: Yes(11) No(3)
• no. of ways are rrrb=4!/3!=4,bbbr=4!/3!=4.
  therefore no. of ways are=8.probability is 1 in 8.i.e 1/8
• 11 years agoHelpfull: Yes(2) No(6)
• ans is 1/8
• 11 years agoHelpfull: Yes(1) No(3)
• among 4 picks 3 red and 1 blue=4 ways
  among 4 picks 3 blue and 1 red=4 ways
  probability af each way= (4/8)*(4/8)*(4/8)*(4/8)=1/16
  total probability=1/16*8=1/2
• 11 years agoHelpfull: Yes(1) No(1)
• among 4 picks 3 red and 1 blue=4 ways
  among 4 picks 3 blue and 1 red=4 ways
  probability af each way= (4/8)*(4/8)*(4/8)*(4/8)=1/16
  total probability=1/16*8=1/2
• 11 years agoHelpfull: Yes(1) No(0)
• among 4 picks 3 red and 1 blue=4 ways
  among 4 picks 3 blue and 1 red=4 ways
  probability af each way= (4/8)*(4/8)*(4/8)*(4/8)=1/16
  total probability=1/16*8=1/2
• 11 years agoHelpfull: Yes(1) No(1)
• acc 2 me c. is correct....
  
• 11 years agoHelpfull: Yes(1) No(1)
• 1/4 wilbe the correct ans
  probability to draw 3 red hats=1/2*1/2*1/2=1/8
  probability to draw 3 blue hats=1/8
  total probability=1/2*1/2*1/2=1/8+1/2*1/2*1/2=1/4
• 11 years agoHelpfull: Yes(1) No(0)
• order matters in this ...so 4 cases of each red and blue are there
  firstly exactly 3 red is 4/8*4/8*4/8*4/8=1/16 *4=1/4
  exactly 3 blue is 4/8*4/8*4/8*4/8=1/16 *4=1/4
  1/4+1/4=1/2
  ans. 1/2
• 11 years agoHelpfull: Yes(1) No(0)
• answer is 1/2
  
• 11 years agoHelpfull: Yes(0) No(2)
• 1/8 will be the answer !!!
• 11 years agoHelpfull: Yes(0) No(1)