A piggy bank contains hundred 50 p coins, fifty ₹ 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, what is the probability that the coin will not be a ₹ 5 coin?

Given:

A piggy bank contains hundred $50\ p$ coins, fifty $Rs.\ 1$ 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.

To do:

We have to find the  probability that the coin will not be a $Rs.\ 5$ coin.

Solution:

Total number of coins in the piggy bank $=100+50+20+10=180$

Let $E$ be the event of getting a $Rs.\ 5$ coin.

Number of possible outcomes $=180$

Number of outcomes favorable to event $E=10$

$\therefore P( E) = \frac{Number\ of\ favourable\ outcomes}{Total\ number\ of\ possible\ outcomes}$

$= \frac{10}{180}$

$= \frac{1}{18}$

$\therefore P( not\ getting\ a\ Rs.\ 5\ coin )=P(\overline E)$

$= 1 - P( E)$

$= 1 - \frac{1}{18}$

$= \frac{17}{18}$

Therefore, the probability of not getting a $Rs.\ 5$ coin is $\frac{17}{18}$.

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Updated on: 10-Oct-2022

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