For one toss of a certain coin, the probability that the outcome is heads is 0.6. If this coin is tossed 5 times, which of the following is the probability that the outcome will be heads at least 4 times?
~$0.6^{5}$~
~$2\left ( 0.6 \right )^{4}$~
~$3\left ( 0.6 \right )^{4}\left ( 0.4 \right )$~
~$4\left ( 0.6 \right )^{4}\left ( 0.4 \right )+\left ( 0.6 \right )^{5}$~
~$5\left ( 0.6 \right )^{4}\left ( 0.4 \right )+\left ( 0.6 \right )^{5}$~
【思路】最少有四次的頭表示 : 四次有頭的機率(不管順序) + 五次全頭的機率
=(0.6)^4 * 0.4 * C4 5 + (0.6)^5
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