Maths Help? (1 Viewer)

[fatima96]

In a mixture of brown and white pebbles in a gravel, brown and white pebbles occur in the ratio 2:3. If 3 pebbles are chosen, what is the probability that at least 1 is white.
I know how to get the answer and everything but I just don't know why. I want to understand why I'm using all these methods but I don't.

 

[Shadowdude]

Try a tree diagram?

 

[fatima96]

I got the answer, I just have no clue why :S
Like why do you do 1 - (2/3) ^3 :SSSS
I know it is complementary, but why do we cube 2/3 :}

 

[Shadowdude]

Umm, isn't the answer 1 - (2/5)^3 ?

or is my brain not working again

 

[fatima96]

Yeah thats it, but why :|

 

[Spiritual Being]

I'll assume there is a large number of pebbles.
The probability that all three that are chosen are brown is 2/5 x 2/5 x 2/5 = 8/125
The complementary event is that at least one pebble is white.
So the probability that at least one is white is 1 - 8/125 = 117/125


General math skills <3

 

[Shadowdude]

^ Yeah that.

Take these things logically. Draw a diagram - like for me, I like tree diagrams.

 

[RivalryofTroll]

I'll assume there is a large number of pebbles.
The probability that all three that are chosen are brown is 2/5 x 2/5 x 2/5 = 8/125
The complementary event is that at least one pebble is white.
So the probability that at least one is white is 1 - 8/125 = 117/125


General math skills <3

Not even, Year 9 or 10 Maffs skills at max

 

[wildchild666]

Not even, Year 9 or 10 Maffs skills at max

I think they're pretty much the same thing ;P

 

[Spiritual Being]

I answered a 4 unit question the other day, go look at my posts lmaooo

and year 9 and 10 maths is the same thing as general thus far... but won't be the same forever
Still simple math and that's all that matters.

 

[bleakarcher]

^ I'm confused are you a troll or wut?

 

[SpiralFlex]

I dropped general maths to do 3U (No joke)

 

[Demento1]

I do year 10 maths...

 

[RivalryofTroll]

10.3 vs General Year 12, which one is harder?

 

[Spiritual Being]

10.3 vs General Year 12, which one is harder?

10.3....


10.1 is shit math (this is for people who won't be doing math in year 11 or 12 or MAYBE general if they do well)
10.2 (general math just gets slightly harder than this)
10.3 (2 unit)


and @ the guy who asked me I'm a troll
I don't know...
I do general math but I answer 3 and 4 unit questions on this forum...life goes on

 

[wildchild666]

10.3 vs General Year 12, which one is harder?

I say 10.3. Some General year 12 questions are pretty much primary school work.

 

[bleakarcher]

10.3 vs General Year 12, which one is harder?

you mean 5.3

5.3 would probably be a more difficult course

 

[bleakarcher]

I say 10.3. Some General year 12 questions are pretty much primary school work.

i know it wasnt intentional

but that made me lol

 

[mirakon]

A 4u student probs wont be able to get 100% in general

The content is entirely different as u learn stats etc.

 

[barbernator]

spiritual being is trolling this "general maths" thing so hard. We know he is a secret basement 4u study asian.