Question

Question 10 (ii)
A piggy bank contains hundred 50 p 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 will not be a Rs. 5 coin?

Answer 1

Total number of coins in a piggy bank = 100+50+20+10 = 180
$\therefore$ Total number of elementary events = 180
There are 100+50+20 = 170 coins other than Rs. 5 coin.
$\therefore$ Favourable number of elementary events = 170
$\therefore$ P (falling out of a coin other than Rs. 5 coin) = $\frac{170}{180}=\frac{17}{18}$