Question 136030This question is from textbook Holt Algebra I Texas
: A number cube is rolled three times. What is the probability of rolling a 5 at least once?
I know that everytime there is a 1 in 6 chance of getting a 5. So in three rolls that would be 3 chances in 18. So to get it at least once-would it be a 1 in 18 chance?
This question is from textbook Holt Algebra I Texas
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A number cube is rolled three times. What is the probability of rolling a 5 at least once?
I know that everytime there is a 1 in 6 chance of getting a 5. So in three rolls that would be 3 chances in 18. So to get it at least once-would it be a 1 in 18 chance?
-------------------
Your problem is called a binomial problem because with each roll of the
dice you either get a 5 or you don't.
-------------------
You want the probability of getting one five, or two fives, or three fives
.
The only thing you do not want is no-fives in three rolls.
--------------------------------------------
So the way this problem is done is to figure out the problem of no-fives
in three rolls, which is (5/6)^3, and then subtract that from "1" which
covers the probability for all the possible 3-throw outcomes.
So you get P(at least one 5 in three throws) = 1-(5/6)^3 = 0.4213...
================
Cheers,
Stan H.
|
|
|
