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#1 2016-06-10 10:44:04

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,226

Probability and Geometry Unit HW help

1. A bag contains 3 red marbles, 3 blue marbles, and 3 yellow marbles. 2 marbles are chosen randomly WITHOUT replacement. Find the probablity that both marbles chosen ARE the SAME color.

Reasoning: 3/9 * 2/8 = 6/72 = 1/12.

2. What is the area of a isosceles right triangle with a hypotenuse of 20 inches?

Reasoning: 1:1:√2
so
20/√2 * 20/√2 = 400/2 = 200/2 = 100/2 = 50
^ 1/2BH

3. If 400 were to be expressed as a sum of AT LEAST 2 distinct powers of two, what would be the least possible sum of the powers? i.e, 2^2 + 2^3 = 12, 2+3 =5.
Reasoning: Have no idea on how to approach effectively. tried for 20 mins and found nothing.

4. How many positive 5 digit numbers have 123 AS A BLOCK. 2 such numbers are 12399 and 91239
I said 300

5. If (4^5)(5^13) is written as a integer, how many digits are in it?
Reasoning: 12?


The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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#2 2016-06-10 13:53:06

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Probability and Geometry Unit HW help

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#3 2016-06-10 15:44:59

thickhead
Member
Registered: 2016-04-16
Posts: 1,086

Re: Probability and Geometry Unit HW help


Last edited by thickhead (2016-06-10 15:49:32)


{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}

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#4 2016-06-11 00:33:25

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,226

Re: Probability and Geometry Unit HW help

Bobbym, can you explain why it is 9/9 for the first question?

bobbym wrote:

Hi;

Hey bobbym, how did you find the 3 exponents that add up to 400? Guess and check?


The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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#5 2016-06-11 03:48:11

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Probability and Geometry Unit HW help

Hi;

Bobbym, can you explain why it is 9/9

There are 9 total balls and you can pick anyone of the 9 first so 9 / 9. Once you have picked anyone of them there are only 2 left of that color.

Hey bobbym, how did you find the 3 exponents that add up to 400? Guess and check?

A simple program would have been fastest but I used generating functions instead. This will seem like overkill but it is more in keeping with the Teakettle Principle.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#6 2016-06-12 04:08:44

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,226

Re: Probability and Geometry Unit HW help

bobbym wrote:

Hi;

Bobbym, can you explain why it is 9/9

There are 9 total balls and you can pick anyone of the 9 first so 9 / 9. Once you have picked anyone of them there are only 2 left of that color.

Hey bobbym, how did you find the 3 exponents that add up to 400? Guess and check?

A simple program would have been fastest but I used generating functions instead. This will seem like overkill but it is more in keeping with the Teakettle Principle.

Bobbym, my teacher said not to use a computer on the powers problem. Is there a reasonably easy and simple way?


The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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#7 2016-06-12 04:24:07

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Probability and Geometry Unit HW help

It depends on what he thinks is reasonable. What solution does he/she give?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#8 2016-06-12 04:35:59

thickhead
Member
Registered: 2016-04-16
Posts: 1,086

Re: Probability and Geometry Unit HW help


{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}

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#9 2016-06-12 04:51:54

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Probability and Geometry Unit HW help

Is there a reasonably easy and simple way?

I did not recomend the idea of expressing the number in binary because whether or not you can do it easily by hand depends on the size of the number.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

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