## Monday, 17 September 2012

### Probability Group Activity - Group 3

(a) Flipping a coin and getting heads, then flipping it again and getting tails

Ans: Independent.  Flipping heads the first time does not mean that the coin will be more/less likely to land tails the second time. The chances are still 1/2.

(b) Rolling doubles with two dice, then rolling doubles again.

Ans: Independant. Rolling doubles the first time does not make it more/less likely that a double will be rolled a second time. The dice cannot "remember" its previous result and change the next result.

(c) Drawing (and removing) two aces from a normal deck cards, then drawing kings.

Ans: Dependant. After removing the 2 aces, there are less cards in the deck, so the deck "remembers" that 2 aces are already picked, so it is more likely that a king will be picked.

(d) Drawing (and removing) a red ball initially containing two red balls and three white balls, then drawing a white ball.

Ans: Dependent. After removing the first red ball, there are less balls in the bag, so there is a higher chance of picking a white ball.

(a) 13/100 x 8/100 = 13/1250

(b) 1/6 x 1/6 = 1/36

(c) 1/52 x 1/52 = 1/2704

(d) 1/100 x 1/100 = 1/10000

Example 13

P(Getting heads 3 times in 3 tosses)
= 1/2 x 1/2 x 1/2
= 1/8

1. They could have written P(x)= answer for mini task 5, so that its clear what is the probability for.

2. Mini Task 4 part b) One can only roll doubles using two dice, does that make them dependent?

3. Chin Wai Kit9/18/2012 10:32 am

Very Clear, but for example three, if they had posted the question, it would have been better

4. It is very clear and well done. Maybe define what independent and dependent events are?

5. @shiying, weather or not the 2 dice will show the same number (making it a double) is dependent as weather or not we get a double on the second throw is dependent on the first throw.. But the example is talking about the event (rolling a double) happening twice. If we roll a double once, it does not affect weather we are more likely to roll a double

6. Very in-depth but should include a summary of what independent events are

7. Needs some Diagrams or photo but well explained

8. Very clear explanation however adding a question might have been better

9. For Mini task 4, they can describe what is the difference between independent and dependent events so that it will be easier to understandt mini task 4.

10. Diagrams or tables would help in the understanding

11. This is a very clear and elaborate guide. However, it would have been better if there were pictures to help the viewer visualise the question better.

12. Diagrams or photos would make the explanation clearer.

13. Along with some pictures, I think that it would be better to establish what 'dependent' and 'independent' events are before going on to provide examples to further explain your point.