alleryIf a fair coin is tossed twice and $X$ = number of heads, then $P[X = 1]$ equals:
A$1/4$
B$3/4$
C$2/3$
D$1/2$
Answer & Solution
Correct answer: D. $1/2$
$X = 1$ corresponds to events {HT, TH}, so $P[X=1] = 2/4 = 1/2$.
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