Question

If a coin is tossed twice, find the probability of getting at least one head.

• A. $\frac{1}{2}$
• B. $\frac{1}{4}$
• C. $\frac{3}{4}$
• D. $\frac{2}{3}$

Answer 1

The correct option is C $\frac{3}{4}$

The only way in which at least one head will not occur is if both tosses give tails.

$S=HH,HT,TH,TT$

The probability of this is the probability of a single tails multiplied by itself.

The probability of this is approximately $\frac{1}{2}$, so the probability of two in a row is $\frac{1}{2}$$\ast \frac{1}{2}=$$\frac{1}{4}$

If the probability of getting no heads is 14 , the probability of getting at least one head is $1-$$\frac{1}{4}$=$\frac{3}{4}$