Question

Two unbiased coins are tossed. If one coin shows head, the probability that the other also shows head is ____

• A. $\frac{1}{4}$
• B. $\frac{1}{2}$
• C. $\frac{1}{8}$
• D. $1$

Answer 1

The correct option is A $\frac{1}{4}$

Two unbiased coins are tossed...

so, sample space,$S=\left\{\right(T,T),(T,H),(H,T),(H,H\left)\right\}$

number of sample space, $n\left(S\right)=4$

favourable outcomes , $n\left(E\right)=1$ [ because other coin also shows Head has only one possibility e.g., $(H,H)$]

now, probability that other coin also shows head , $P\left(E\right)=\frac{n\left(E\right)}{n\left(S\right)}=\frac{1}{4}$