Probability Question (1 Viewer)

[IAU001]

A fair six faced die with faces numbered 1,2,3,4,5,6 is tossed seven times. What is the probability that a "6" occurs on exactly two of the seven tosses?


ANSWER: 21857/933121 = approx 0.2344

Thanks in advance

 

[Fortify]

P(2 sixes) = 7C2 * (1/6)^2 * (5/6)^5 = 0.234428583

 

[Da Nawty Dragon]

why do u have to multiply it by 7C2 at the start?

 

[addikaye03]

why do u have to multiply it by 7C2 at the start?

The binomial distrubution formula is P(X=R)=nCr p^k q^n-k where p is the successful attempts and q= is the unsuccessful ( ie.1-p). So as you can see nCr is inclusive.

-But the reason behind the nCr is that the successful attempts could occur at anytime throughout the 7 tosses. There is no order.

 

[IAU001]

ohk cool thanks guys!