Destroyer QR #64

[D.D.S.]

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Hi, I dont understand the solution to this problem. Is there something that im missing, or is there an error in the solution because it states that
P=(nCr)(p)^n (1-p)^r.

for nCr, n = 3 and r = 2 but then the exponents on p is 2 and (1-p) is 1.
Why are these different? Can someone help me out with this?


Thanks.

 

[Streetwolf]

Hi, I dont understand the solution to this problem. Is there something that im missing, or is there an error in the solution because it states that
P=(nCr)(p)^n (1-p)^r.

for nCr, n = 3 and r = 2 but then the exponents on p is 2 and (1-p) is 1.
Why are these different? Can someone help me out with this?


Thanks.

Should be p^(r) and (1-p)^(n-r).

 

[tgutberg]

Can someone please explain to me why for that question it is not just 0.7*0.7*0.3?

 

[futuredentist07]

Can someone please explain to me why for that question it is not just 0.7*0.7*0.3?

talk to larry guys..hes in charge of the QR section of the dat destroyer!

 

[Streetwolf]

Can someone please explain to me why for that question it is not just 0.7*0.7*0.3?

I don't know what the question is, but judging from the OP I'd say the following:

You need to consider 0.7*0.7*0.3.
You need to consider 0.7*0.3*0.7.
You need to consider 0.3*0.7*0.7.

So you add all three of those because it can happen in any three of those orders. That's why you have nCr in the beginning of the formula.