A fair die is thrown. Let $X$ = number of factors of the number on the upper face. $P[X = 2]$ equals:
A$1$
B$1/6$
C$2/6$
D$3/6$
Answer & Solution
Correct answer: D. $3/6$
Number of factors: 1→1, 2→2 (1,2), 3→2 (1,3), 4→3 (1,2,4), 5→2 (1,5), 6→4 (1,2,3,6). So $X=2$ for {2,3,5} — 3 outcomes. $P[X=2] = 3/6 = 1/2$.
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