Question

I know how to solve the problem I'm just not sure how to get q in this probability problem

42% of students at a college are full time. If 7 students are randomly selected what is the probability 4 are full-time?

Answer 1

I know that n=7
x=4
p=.42

Answer 2

p+q=1

Answer 3

In my notes I have q=P(failure) =1-p

Answer 4

yes, solve the equation i wrote for p and you'll get exactly that.

Answer 5

so .42 plus

Answer 6

oops, i mean q

Answer 7

no... think is you bought something for 42 cents and you paid with a 1 dollar bill. what would your change be?

Answer 8

.58

Answer 9

that's q

Answer 10

is that how you always get q though?

Answer 11

\[P(x=4)=\left(\begin{matrix}7 \\ 4\end{matrix}\right)(.42)^4(.58)^3\]

Answer 12

yep.

p+q=1 so q = 1-p and p = 1-q

p and q are complements in the sense that their sum is 1. this is always true for binomial probabilities.

Answer 13

ooh okayy got it. Thankss(:

Answer 14

just like n = x + (n-x)

Answer 15

\[P(X=k)=\left(\begin{matrix}n \\ k\end{matrix}\right)p^kq^{n-k}\]

Answer 16

you're welcome!