Question
#
A stoplight at the corner of Lincolnway and Duff Avenue is red 20% of the time. For
someone who drives through this stoplight 10 times a week, what is the
probability that they will stop at least three times?
a: .201
b: .771
c: .878
d: .322
A stoplight at the corner of Lincolnway and Duff Avenue is red 20% of the time. For
someone who drives through this stoplight 10 times a week, what is the
probability that they will stop at least three times?
a: .201
b: .771
c: .878
d: .322
Answers
Kate
My stats book wasn't very helpful in the teaching of this. I'm not really sure how to do it, so if you could teach me some EASIER methods, I would greatly appreciate it!
MathGuru
You can use a binomial probability table (which is much easier) or do this by hand with the following formula:
P(x) = (nCx)(p^x)[q^(n-x)]
x = 0, 1, 2
n = 10
p = .2
q = 1 - p = 1 - .2 = .8
Calculate P(0), P(1), and P(2).
Add P(0), P(1), and P(2) probabilities together, than subtract this value from 1. You should have your answer!
I hope this helps.
P(x) = (nCx)(p^x)[q^(n-x)]
x = 0, 1, 2
n = 10
p = .2
q = 1 - p = 1 - .2 = .8
Calculate P(0), P(1), and P(2).
Add P(0), P(1), and P(2) probabilities together, than subtract this value from 1. You should have your answer!
I hope this helps.
Kate
Got it! Thanks!!