Simple stats question or am I missing something?

Question

Preparing for my stats final here... I must be missing something really simple or this question is just too easy. Here is the question:

5. An oil prospector will drill a succession of holes in a given area to ﬁnd a productive well. The probability
that he is successful on a given trial is 0.2.
a. (4 pts) What is the probability that the third hole drilled is the ﬁrst to yield a productive well?
b. (6 pts) If the prospector can aﬀord to drill at most four wells, what is the probability that he will
fail to ﬁnd a productive well?

my answers:

a) $ (0.8)^2(0.2) $
b) $(0.8)^4$

I'm sure there is more to this problem, can someone please help? thx

score 2 · Accepted Answer · answered Dec 13 '13 at 06:13

2

As far as I can tell, you're perfectly correct.

Once you know the rules, questions like this can be quite easy, but you might be surprised as to how difficult some students can find them.

answered Dec 13 '13 at 06:13

William Ballinger

3,682

wow, that does indeed surprise me. Thanks for the feedback. I'm an undergrad student and I thought I must have missed something because there were 10 questions on a 3 hour long exam and this was one of them. – Sam Creamer Dec 13 '13 at 15:21

Simple stats question or am I missing something?

1 Answers1