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# Tossing a coin, the probability of getting a head is 0.6. If

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Tossing a coin, the probability of getting a head is 0.6. If [#permalink]  25 Jan 2008, 22:52
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Tossing a coin, the probability of getting a head is 0.6. If a coin is tossed for 5 times, what is the probability of getting at least 4 heads?

A. (0.6)^4 * 0.4
B. (0.6)^5
C. 0.8 * (0.6)^5
D. 2.6 * (0.6)^4
E. (0.4)^5 * 0.6

Could you please explain in detail?
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Concentration: Entrepreneurship, Other
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Re: PS - Prob. of tossing a coin [#permalink]  25 Jan 2008, 23:56
Expert's post
D

we use formula: $$p=C^n_m*q^{m}*(1-q)^{n-m}$$

$$p=C^5_4*(0.6)^4*(0.4)^1+C^5_5*(0.6)^5*(0.4)^0=(0.6)^4*(5*0.4+0.6)=2.6*(0.6)^4$$
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Re: PS - Prob. of tossing a coin   [#permalink] 25 Jan 2008, 23:56
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