Subject: General Aptitude · Chapter: Probability · Exam: · Marks: · Difficulty:
In a simultaneous throw of two coins, the probability of getting at least one head is
(a)$\frac{1}{2}$
(b)$\frac{1}{3}$
(c)$\frac{2}{3}$
(d)$\frac{3}{4}$
Answer
Answer (as printed): D
Explanation
Here $S=\{\mathrm{HH}, \mathrm{HT}, \mathrm{TH}, \mathrm{TT}\}$. Let $E=$ event of getting at least one head $=\{\mathrm{HT}, \mathrm{TH}$, $\mathrm{HH}\}$. $$\therefore \quad P(E)=\frac{n(E)}{n(S)}=\frac{3}{4} .$$
Explanation as extracted from the printed page; notation may be imperfect.