Question

A piggy bank contains hundred 50 paise coins, fifity ₹1 coins, twenty ₹2 coins and ten ₹5 coins. If it is equally likely that one of the coins will fall out when the bank is turned upside down, find the probability that the coin which fell  will be a ₹1 or ₹2 coin    

Answer 1

Total number of coins = 100 + 50 + 20 + 10 = 180
So, the total number of outcomes is 180. 

Number of ₹1 or ₹2 coins = 50 + 20 = 70
So, the favourable number of outcomes are 70.
∴ P(the coin which fell will be a ₹1 or ₹2 coin ) = \[\frac{\text{ Favourable number of outcomes }}{\text{ Total number of outcomes }} = \frac{70}{180} = \frac{7}{18}\]