Question

A piggy bank contains hundred 50p coins, fifty Re. 1 coins, twenty Rs. 2 coins and ten Rs. 5 coins. If it is equally likely that one of the coins will fall out when the bank is turned upside down, what is the probability that the coin 

(i) will be a 50 p coin ? 

(ii) will not be a Rs. 5 coin ?

Answer 1

Number of 50 ps coins = 100 

Number of Re. 1 coins = 50 

Number of Rs. 2 coins = 20 

Number of Rs. 5 coins = 10 

∴ Total number of coins, n(S) = 180 

(i) Possibility of one 50 ps coin : 

n(A) = 100

(ii) Possibility of one Rs. 5 coin: 

n(B) = 180 – 10 = 170 

(∵ 10 coins are Rs. 5)