116,651 views
4 votes
4 votes
College Math- Probability (Help appreciated!!!!) (please no links! :) )

A pair of fair dice is rolled. E is the event that the first dice rolls a 3 and F is the event that the sum of the two dice is 6. Are E and F independent events?

User SaphuA
by
2.9k points

1 Answer

19 votes
19 votes

Answer:no they are not independent

Explanation:

1) in order for events to be independent the probability of E happening should equal the probability of E happening given that F has already happend

2) P(E)=1/6 (on 6 sided die there is only 1 face that has 3 hence probability of e occurring is 1/6) or .167

3) P(E | F) read as probability of E happening given F has occurred

(Probability of E * probability of F) / total number of outcomes in F

probability of F= 1/6 as there is only one face(3) which will make the sum of the 2 die 6

(1/6)(1/6)/6=0.004

P(E)= .1167

P(E| F) =.004

hence probability aren't equal as making F happen impacts E'E's chances

ANOTHER way to think about this is if E rolls a 3 then the only way to make the sum of the 2 dice equal 3 is if die 2 rolls 3 as well. Hence the pprobability Of the second outcome tht sum of 2 die=6 depends on the number the first die lands

User Andrew Jens
by
3.2k points