Question

A piggy bank contains a hundred $50p$ coins, fifty $Rs1$coins, twenty $Rs2$ coins, and ten $Rs5$ 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 $Rs5$coin?

Answer 1

Given ,

Number of $50p$coins $=100$

Number of $Rs1$coins $=50$

Number of $Rs2$coins $=20$

Number of $Rs5$ coins $=10$

Total number of coins $=100+50+20+10$

$=180$

We know that,

$\therefore$ the probability that the coin will be a $Rs5$ $=\frac{10}{180}$

$$\begin{gathered} =\frac{1}{18} \\ =0.055 \end{gathered}$$

Now,

the probability that the coin will not $Rs5=1-$the probability that will be a $Rs5$

$$\begin{gathered} =1-0.055 \\ =0.945 \end{gathered}$$

Hence, the required solution is $0.945$ .