Probability on marbles
Favorites|Homepage
Subscriptions | sitemap
HOME > Mathematics > Probability on marbles

Probability on marbles

[From: ] [author: ] [Date: 11-05-08] [Hit: ]
four green ones, five white ones, and two purple ones. She grabs eight of them. Find the probability of the following event, expressing it as a fraction in lowest terms.......
Recall from Example 1 that whenever Suzan sees a bag of marbles, she grabs a handful at random. She has seen a bag containing four red marbles, four green ones, five white ones, and two purple ones. She grabs eight of them. Find the probability of the following event, expressing it as a fraction in lowest terms. HINT [See Example 1.]
She has all the red ones.

-
There are 15 marbles in the bag, so there are
15C8 = 15! / (8! 7!)
= 15*14*13*12*11*10*9 / (7*6*5*4*3*2*1)
= 13*11*5*9 = 6,435 different combinations of 8 of them.

The number of different combinations including all 4 red ones is the number of different ways 4 of the other 11 marbles can be combined:
11C4 = 11! / (7! 4!)
= 11*10*9*8 / (4*3*2*1)
= 11*10*3 = 330

So the probability is
330/6,435 = 2/39
1
keywords: on,marbles,Probability,Probability on marbles
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .