Discussion
A six-faced fair dice is rolled five times. The probability (in %) of obtaining "ONE" at least four times is
Answer: C
The probability is about 0.33%.
"At least four" means exactly four ones or exactly five, using the binomial distribution with p = 1/6:
\[ \begin{aligned} P &= \binom{5}{4}\left(\frac{1}{6}\right)^{4}\frac{5}{6} + \left(\frac{1}{6}\right)^{5} \\ &= \frac{25 + 1}{7776} = 0.00334 \end{aligned} \]
As a percentage that is 0.334%, which rounds to 0.33. 3.33 and 33.3 are ten and a hundred times too large, the decimal slips of not converting correctly to a percentage, and 0.0033 is the probability itself left as a fraction rather than a percentage.
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