Heather C.

asked • 02/26/14

math questions(probability)

you roll a fair die one time. What is the probability of rolling a 3 or 4?
A fair die is flipped 4 times. What is the probability of getting "heads" on all 4 flips?
A fair coin is flipped 4 times. What is the probability of getting at least one tail on the four flips?
An urn contains 6 green and 8 yellow balls. You randomly choose 2 balls(without replacement)
--Probability of both balls being green.
--Probability that at least one ball will be yellow

Heather C.

I'm confused on the green and yellow probability
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02/27/14

Parviz F.

Outcome of event of drawing 2 balls from the green can happen as:
 
{ ( yellow, green) ( green ,yellow) ( green , green ) ( Yellow, yellow)}
 
   a) Pr ( green, Green) = 6/14 * 6/14 = 3/7* 3/7 = 9/49
   b)   Pr( at least one yellow), occurrence of all 3 cases other than ( green, green) will have 1 or 2 yellows in.
    Therefore, if we take away probability of ( green , green) , part a from 1, we have the probability of at least one yellow.
 
     1 -  7/9 = 40/9
 
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02/28/14

1 Expert Answer

By:

Parviz F. answered • 02/26/14

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Mathematics professor at Community Colleges

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a)Probability of 3 or 4 = 1/6 + 1/6 = 1/3
 
b)  ( 4 ) ( 1/2) ^4  ( 1/2) ^0  =
   ( 0 )
 
     4 !     * (1/2 ) ^4 = 1/16
    4 ! 0 !
   c)
       6/14 * 6/14 = ( 3/7) ^2 = 9/49
 
   d) 1 - Pr( green, green) = 1 - 9/49 = 40/49
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Parviz F.

In Comments: 1st line should be:
 
 Outcome of drawing 2 balls from the urn will have 4 possible outcome as follows:
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02/28/14

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