P5 Maths: Stats and Probability: Help needed!

[JackRabbit]

good, thanks for all the feedback. It makes sense the answer is 9 and the detailed explanation above helps. I agree this (even though it is under the probability topic) looks more like a logical analysis question.

[Knoobie]

Misinterpreted the question.

Edited November 12, 2013 by Knoobie

[JackRabbit]

how do a I close a thread? The original question has been satisfactorily answered.

[Darryn]

Can I answer 0 or infinity?

 

Explanation -

neither black nor white, strictly speaking are colours.

On a printed sheet - white is the absence of colour.

 

When talking on the light spectrum, black is the absense of light, while white is all colours in balance (remembering that colours are actually represented by the refraction of light)

 

So my answer is - both black and white are virtual constructs rather than "real" items - so you answer must be zero or infinity, since no other option is possible.

[Premacist]

Anyone remember the movie 21?

 

Just to add, the initial part of the movie where there is 3 windows open and the host ask about which one you'll choose..

 

 

Maybe it is something like that..

 

8+5 = 13

 

so initially you have 8/13 chance of getting white and 5/13 chance of getting black..

 

Chances of White 8/13 = 61.6%

chances of black 5/13 = 38.5%

 

So you need to work out a method to try to even the chance to 50% each.

 

As pointed out, that was not a probability question but a logical thinking question,

 

If you want to calculate the minimum chips, i.e. 2 chips to take out with one white and one black, the probability will be:

 

Probability for the first to be white: 8/13

Probability for the second to be black: 5/12

Probability for white follow by black: 8/13 x 5/12 = 10/39

 

Probability for the first to be black: 5/13

Probability for the second to be white: 8/12

Probability for black follow by white: 5/13 x 8/12 = 10/39

 

So, probability for either white follow by black or black follow by white

= 10/39 + 10/39

= 20/39

[Evillusion]

teacher must be thinking of playing roullette.....should be red or black...not white or black....maybe can also big or small....

[Sabretan]

 

Shouldn't the answer be 2?

 

If question changed to "What is the maximum number of chips..." then it should be 9

 

 

Cool, I like your way of thinking.

 

Reminds me of this,

 

Winning 4D or winning Toto is 50-50.

 

Either u win or u don't.

how do a I close a thread? The original question has been satisfactorily answered.

 

 

wah Jack Rabbit,

 

did u praise all the useful replies?

 

 

muz 感恩ok.

Edited November 13, 2013 by Sabretan

[Cindytan]

Question:

There are 8 white poker chips and 5 black poker chips in a bag.

What is the minimum number of chips to take out (without looking) to be sure that you have one chip of each color?

 

Please explain how to derive the answer - thanks!!

minimum should be 1 if its more than 4 for example 5 and the suay suay first 5 took out are all the 5 black poker chips?

Edited November 13, 2013 by Cindytan

[Sosaria]

I don't think 9 is the maximum number of chips, and 2 is the minimum number...

 

That's thinking too much about the question wordings and sometimes confuse ourselves.

 

The questions says "minimum number", but it also states "to be sure".

 

Only by drawing at least 9 chips without looking, can we ever be very sure or guaranteed, 100% sure.

 

Draw 2 chips is the minimum number to get at least one colour each, but can't say for sure leh...

[Viceroymenthol]

Wah lau.... you all ang moh fail is it?

 

What is the minimum number to be sure. The answer is 9 lor! Any number FEWER than 9, you CANNOT be sure. So the MINIMUM is 9.

 

I think this has to do with the students' understanding of the language. Nowadays Primary School maths is language-based and problem-solving based. If command of language is no good and cannot accurately grasp the intent and purpose of the question, sure misunderstand and answer wrongly.

 

Last time, during my time, if ang moh no good, still can score high in Maths, cos just numbers only.... Now, a bit difficult lah....

[Little_prince]

so looks like no simple explanation, huh....... thinking how come I find this question quite tricky to answer....

any number 1-8 has a probability of grabbing one colour. Eg all black. Next highest number is 9. Which is 100% both colour

[Premacist]

Wah lau.... you all ang moh fail is it?

 

What is the minimum number to be sure. The answer is 9 lor! Any number FEWER than 9, you CANNOT be sure. So the MINIMUM is 9.

 

I think this has to do with the students' understanding of the language. Nowadays Primary School maths is language-based and problem-solving based. If command of language is no good and cannot accurately grasp the intent and purpose of the question, sure misunderstand and answer wrongly.

 

Last time, during my time, if ang moh no good, still can score high in Maths, cos just numbers only.... Now, a bit difficult lah....

 

Wait till you see those question with overlapping pattern of circles, semi circles, square or triangle and ask you to find the area of shaded part or unshaded part. I don't think we were tested during our time on such question.

[Little_prince]

Question:

There are 8 white poker chips and 5 black poker chips in a bag.

What is the minimum number of chips to take out (without looking) to be sure that you have one chip of each color?

 

Please explain how to derive the answer - thanks!!

P (get both colour)= 1- p(all one colour) hence 100% both colour is when p (getting one one colour)=zero.

 

Which is > 9

 

Since question asked for minimum. Hence answer =9

[1fast1]

This is not so much a probability problem, as it is one exploiting the Pigeonhole Principle: http://en.wikipedia.org/wiki/Pigeonhole_principle