Question

Churna has a pack of playing cards.She takes out a card. Its red heart king. Now, without placing back the card into the deck, she pulls out all the royal cards from it (king, queen and jacks) What is the probability of getting a card having a prime number. ??

Answer 1

Number of cards = 52
She pulls out a king, so cards left = 52-1 = 51

Now, she takes out all the remaning kings, queens and jacks,so cards left = 51 - 11 = 40

Number of Prime numbers between 2-10 = {2,3,5,7} = 4
How may cards have these numbers ? 4 × 4 = 16

So, probability of getting a prime number = 16/40 = 8/20 = 4/10 = 2/5

Answer 2

She pulls out a king, so cards left = 52-1 = 51 Now, she takes out all the remaning kings, queens and jacks,so cards left = 51 - 11 = 40 Number of Prime numbers between 2-10 = {2,3,5,7} = 4 How may cards have these numbers ? 4 × 4 = 16 So, probability of getting a prime number = 16/40 = 8/20 = 4/10 = 2/5