Question 381264
There is a 1/5 20% probability that one type of appliance will break within 2 yrs. Find the probability that 4 out 15 appliances will break within that time period. I have so far p= 1- (4/15)x 2nd power as my formula. Doesn't look or feel like a good formula where am I going wrong. 
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Binomial Problem with n = 15 and p = 0.20
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P(x = 4) = 15C4(0.2)^4*0.6^11 = 0.1876
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Cheers,
Stan H.