Probability. (1 Viewer)

[Paj20]

Is there away to tell if the question wants you to use a Tree Diagram to work out the answer or use the Counting Technique method..?

Just wondering cause sometimes its a bit hard to distinguish which way your actually ment to work out the probability.

For Instance. Q-. From F, G, H, I and J a school captain and vicecaptain need to be elected. Calculate the probabilty that I and J occupy the two positions.

The text book uses the method of - Arrangments - 5x4 = 20

= 2 OVER 20

= 1 OVER 10

But why wouldnt you use a Tree Diagram to work out that Q??

Thanks.

 

[PC]

You could of course use a tree diagram to do the question. You'll find two branches where I and J take up the positions out of the 20 branches, which gives the answer of 2/20 or 1/10.

But there comes a point where making a tree diagram becomes impractical. This is where you'd opt for the calculation.

Practice really.

 

[Paj20]

so you dont really need to do a tree diagram for any of them.. i understand..

kk thanks.

 

[marcquelle]

I the past papers they rarely ask you to do a tree diagram.