In a purse, there are 30 coins, twenty one-rupee and remaining 50-paise coins. Eleven coins are picked simultaneously at random and placed in a box. If a coin is now picked from the box, find the probability of it being a rupee coin.

• it will be 2/3.
  initial probability is 2/3
  so no matter how many u choose it will always remain 2/3
• 10 years agoHelpfull: Yes(25) No(8)
• total coins 30
  1 rupee coins 20
  50 paise coins 10
  
  1 rupee coin probability 20C11
  11 coin are picked 30C11
  ans should be= 20C11/30C11
• 10 years agoHelpfull: Yes(12) No(12)
• @ moumita das : there is some posibilities
  rupee : 50 paisa probabilitie
  11 0 1 or 11/11
  10 1 10/11
  9 2 9/11
  8 3 8/11
  ... ... 7/11
  6/11
  5/11
  4/11
  3/11
  2/11
  1 10 1/11
  
  THEN you can find that 1+2+3+......+11 =66 therefore 66/11
  and these are 11 case so 66/11*11= 6/11
• 10 years agoHelpfull: Yes(9) No(16)
• we have to pick from the box of 11 coins, not from 30 coins purse.
  then how it is 20c1/30c1?
  
• 10 years agoHelpfull: Yes(7) No(1)
• yar amcat question tmlog kyun dalte ho elitmus wale me.amcat wale ko amcat me dalo na faltu time west
• 10 years agoHelpfull: Yes(7) No(2)
• 20c1/30c1=2/3
• 10 years agoHelpfull: Yes(6) No(2)
• it will be : 2/3
• 10 years agoHelpfull: Yes(3) No(1)
• BUT KANHYA LAL THERE IS NO OPTION CALLED 6/11
• 10 years agoHelpfull: Yes(3) No(3)
• upto 66/11 it is ok.what is 66/11*11 ? you had already taken 11 cases so that u added all cases and got finally 66/11. pls explain @KANHAIYA
• 10 years agoHelpfull: Yes(2) No(0)
• The answer is 1/2
  because the chosen coin is either 1-rupee coin or either 50-paise coin.
  
• 10 years agoHelpfull: Yes(2) No(5)
• 20c1/30c1, as we can select a rupee coin from 20 coinsand there are 30 coins in total from which we are picking one coin
  
• 10 years agoHelpfull: Yes(2) No(0)
• 20c1/30c1=2/3 ans
• 10 years agoHelpfull: Yes(1) No(1)
• (2/3*11)
  ------------------------ =2/3
  (2/3*11)+(1/3*11)
• 10 years agoHelpfull: Yes(1) No(0)
• 20C11/30C11 = 2/3Ans
• 9 years agoHelpfull: Yes(1) No(2)
• kanhaya bawala hy kya tane.. chor de padhna tane
• 8 years agoHelpfull: Yes(1) No(1)
• it will be : 13/22
  
• 10 years agoHelpfull: Yes(0) No(5)
• sorry it typed by mistake
  the probability of being a rupee is : 6/11
• 10 years agoHelpfull: Yes(0) No(5)
• how ?? @kanhaiya lal ??
• 10 years agoHelpfull: Yes(0) No(0)
• @ PIYA SHARMA : how 2/3 ?
  
• 10 years agoHelpfull: Yes(0) No(1)
• if anybody can this question step by step plse explain ans is not clear wat is the correct ans for this question
• 10 years agoHelpfull: Yes(0) No(0)
• if anyone have correct ans. then plz tell.....
  
• 10 years agoHelpfull: Yes(0) No(0)
• @ MANSI but there is no option give in this question. so i can't say that my ans is correct or not...
  
• 10 years agoHelpfull: Yes(0) No(0)
• 21C2/30C2=14/29
• 10 years agoHelpfull: Yes(0) No(0)
• it is a question of amcat.. the options are:
  Option 1 : 4/7 Option 2 : 1/2 Option 3 : 2/3 Option 4 : 5/6
• 10 years agoHelpfull: Yes(0) No(0)
• it must be 2/3
  
• 10 years agoHelpfull: Yes(0) No(0)
• 20c1/30c1
  2/3 ANS.....
  WE HAVE 20 1RS COINS.AND WE HAVE TO SELECT 1 COIN SO 20c1
  AND TOTAL WE HAVE 30c1
  
• 10 years agoHelpfull: Yes(0) No(0)
• ans 6/11 is right
• 7 years agoHelpfull: Yes(0) No(3)
• it will be 2/3,because there is 20 one rupee coin and 10 50-paise coin so probability for one rupee coin is 2/3.
• 6 years agoHelpfull: Yes(0) No(0)