Question

Two coins are tossed simultaneously. Find the probability of getting
i) 2 heads
ii) 2 tails
iii) at least one head
iv) at most one tail

Answer 1

Sample space is {HH, HT, TH, TT}
i) We have two heads only once
$\therefore$ P(2 heads) $=\frac{1}{4}$

ii) We have two tails only once
$\therefore$ P(2 tails) $=\frac{1}{4}$

iii) We have at least one head in {HH, HT and TH}
$\therefore$ P(at least one head) $=\frac{3}{4}$

iv) We have at most one tail {HH, HT and TH}
$\therefore$ P(at most one tail) $=\frac{3}{4}$