PP-T2-PS89

[Huang Hsin-Yi]

89. 9835-!-item-!-187;#058&007168
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?

(A) (0.6)^5
(B) 2(0.6)^4
(C) 3(0.6)^4(0.4)
(D) 4(0.6)^4(0.4) + (0.6)^5
(E) 5(0.6)^4(0.4) + (0.6)^5

Ans:E

[小花]

頭像至少四次=4次+5次

5(0.6)^4(0.4)+(0.6)^5

前面乘5的原因是可能第一次是尾
或第二次是尾.....第五次是尾 五種可能