Question

A box containing 55 flash cards showing different numbers on it. If a card is picked up at random from the box, the probability of getting an even number is 1/11. How many cards have odd numbers on them?

Answer 1

S={55}

P(even no)=     F.Outcome   = x/55 
                     Total Outcome  

P(even no) = 1/11 

Therefore,

1/11 = x/55 
x= 5 

Therefore 
no of odd no written card = 55-5 
                                         = 50 

Answer 2

We are given that...

Total Flash cards are 55.

Now, also given that the probability of getting an even number is 1/11.

∴ P(A) = Even Number cards/Total Cards = 1/11

let Even Number cards/1 = Total Cards/11 = k

∴ Total Cards = 11k = 55

k = 5

So, Even Number cards are 1.k = 5

Now Odd Number cards are

= Total cards - Even Number card

= 55 - 5 = 50

So, 50 cards have odd numbers written on it.