0
$\begingroup$

I'm flipping cards from my cot into a trashcan across the room. I make 20% of my shots. What is the probability that I make 7 cards using a single deck?

$\endgroup$
6
  • $\begingroup$ What kinda deck? $\endgroup$
    – k.stm
    Apr 4, 2014 at 21:51
  • $\begingroup$ A regular 52 card deck. $\endgroup$ Apr 4, 2014 at 21:55
  • $\begingroup$ This is a binomial distribution,not a negative binomial distribution $\endgroup$ Apr 4, 2014 at 21:59
  • 1
    $\begingroup$ Exactly 7, or at least 7? $\endgroup$
    – MPW
    Apr 4, 2014 at 22:01
  • $\begingroup$ Exactly 7. Why is it a binomial distribution? $\endgroup$ Apr 4, 2014 at 22:06

1 Answer 1

1
$\begingroup$

Probability of success=0.20

Number of trials=52

$$P(X=7)={52\choose7}\cdot (0.2)^7\cdot (0.8)^{52-7}=0.0745873846=7.46\%$$

if you mean atleast 7,

$$P(X\ge7)=1-P(X<7)$$ $$P(X\ge7)=1-\sum_{k=0}^7{52\choose k}\cdot(0.2)^k\cdot(0.8)^{52-k}$$

$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .