Question 15 Marks
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 50 paise coin.
- Will be of value more than ₹1.
- Will be of value less than ₹5.
- Will be a ₹1 or ₹2 coin.
Answer
View full question & answer→Total number of coins = 100 + 50 + 20 + 10 = 180
So, the total number of outcomes is 180.
$\therefore$ P(the coin which fell is a 50 paise coin)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{100}{180}=\frac{5}{9}$
So, the favourable number of outcomes are 30.
$\therefore$ P(the coin which fell has value more than ₹1)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{30}{180}=\frac{1}{6}$
So, the favourable number of outcomes are 170.
$\therefore$ P(the coin which fell has value less than ₹5)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{170}{180}=\frac{17}{18}$
$\therefore$ P(the coin which fell will be a ₹1 of ₹2 coin)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{70}{180}=\frac{7}{18}$
So, the total number of outcomes is 180.
- Number of 50 paise coins = 100
$\therefore$ P(the coin which fell is a 50 paise coin)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{100}{180}=\frac{5}{9}$
- A coin of value more than 1 can be ₹2 or ₹5 coin.
So, the favourable number of outcomes are 30.
$\therefore$ P(the coin which fell has value more than ₹1)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{30}{180}=\frac{1}{6}$
- A coin of value less than 5 can be 50 paise or ₹1 or ₹2 coin.
So, the favourable number of outcomes are 170.
$\therefore$ P(the coin which fell has value less than ₹5)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{170}{180}=\frac{17}{18}$
- Number of ₹1 or ₹2 coins = 50 + 20 = 70
$\therefore$ P(the coin which fell will be a ₹1 of ₹2 coin)
$=\frac{\text{Favourable number of outcomes}}{\text{Total number of outcomes}}$
$=\frac{70}{180}=\frac{7}{18}$

